View source for Chinese calendar

{{Short description|Lunisolar calendar}}
{{About|the traditional Chinese calendar|the official calendar of modern China|Gregorian calendar|and|Adoption of the Gregorian calendar#China and Taiwan}}
{{See also|Sexagenary cycle}}
{{Distinguish|Republic of China calendar}}
{{Unfocused|date=November 2023}}
{{Use dmy dates|date=January 2020}}
[[File:HK WCD 香港會展 HKCEC WCN 灣仔北 Wan Chai North 香港書展 Hong Kong Book Fair July 2021 S64 80.jpg|thumb|[[Tung Shing]], an almanac closely tied to the traditional Chinese calendar, is vital in many aspects of life, including marking suitable dates related to indigenous beliefs and guiding the selection of the most auspicious days for events like weddings.]]
{{Infobox Chinese
| t = 農曆
| s = 农历
| l = "agricultural calendar"
| p = nónglì
| j = nung4 lik6
| mi = {{IPAc-cmn|n|ong|2|.|l|i|4}}
| ci = {{IPAc-yue|n|ung|4|-|l|ik|6}}
| tp = nóng-lì
| w = {{tone superscript|nung2 li4}}
| bpmf = ㄋㄨㄥˊ ㄌㄧˋ
}}
{{History of science and technology in China}}
[[File:Ancient Beijing observatory 05.jpg|thumb|In ancient China, a vertical pole and a horizontal ruler, aligned north and south on the ground, were used to determine the [[winter solstice]] and the length of the [[tropical year]] by measuring the length of the shadow cast. ]]
The '''Chinese calendar''' is a [[lunisolar calendar]] created by or commonly used by the [[Chinese people]]. While this description is generally accurate, it does not provide a definitive or complete answer. A total of 102 calendars have been officially recorded in classical historical texts.<ref>{{Cite web |title=中国历史上产生过102部历法 |url=http://lsqn.ybask.com/ChinaHistory/other/200703/55707.html |access-date=2025-07-18 |website=lsqn.ybask.com}}</ref> In addition, many more calendars were created privately, with others being built by people who adapted [[Chinese culture|Chinese cultural]] practices, such as the [[Koreans]], [[Japanese people|Japanese]], [[Vietnamese people|Vietnamese]], and many others, over the course of a long history.

A Chinese calendar consists of [[Month|twelve months]], each aligned with the [[Lunar phase|phases of the moon]], along with an intercalary month inserted as needed to keep the calendar in sync with the [[seasons]]. It also features twenty-four [[solar terms]], which track the position of the sun and are closely related to [[climate]] patterns. Among these, the [[winter solstice]] is the most significant reference point and must occur in the eleventh month of the year. Each month contains either twenty-nine or thirty days. The [[sexagenary cycle]] for each day runs continuously over thousands of years and serves as a determining factor to pinpoint a specific day amidst the many variations in the calendar. In addition, there are many other cycles attached to the calendar that determine the appropriateness of particular days, guiding decisions on what is considered [[Luck|auspicious]] or inauspicious for different types of activities.

The variety of calendars arises from deviations in [[algorithms]] and assumptions about inputs. The Chinese calendar is location-sensitive, meaning that calculations based on different locations, such as [[Beijing]] and [[Nanjing]], can yield different results. This has even led to occasions where the [[Mid-Autumn Festival]] was celebrated on different days between [[mainland China]] and [[Hong Kong]] in 1978,<ref>{{Cite web |title=1978年中秋節雙胞事件 天文台編曆的重要性 |url=https://www.hkchronicles.org.hk/%E9%A6%99%E6%B8%AF%E5%BF%97/%E2%BE%83%E7%84%B6/1978%E5%B9%B4%E4%B8%AD%E7%A7%8B%E7%AF%80%E9%9B%99%E8%83%9E%E4%BA%8B%E4%BB%B6-%E5%A4%A9%E6%96%87%E5%8F%B0%E7%B7%A8%E6%9B%86%E7%9A%84%E9%87%8D%E8%A6%81%E6%80%A7 |access-date=2025-07-18 |website=www.hkchronicles.org.hk |language=zh-hant}}</ref> as some almanacs based on old imperial rule. The sun and moon do not move at a constant speed across the sky. While ancient Chinese astronomers were aware of this fact, it was simpler to create a calendar using average values. There was a series of struggles over this issue, and as measurement techniques improved over time, so did the precision of the algorithms. The driving force behind all these variations has been the pursuit of a more accurate description and prediction of natural phenomena.

The calendar during imperial times was regarded as sacred and mysterious. Rulers, with their mandate from Heaven, worked tirelessly to create an accurate calendar capable of predicting climate patterns and astronomical phenomena, which were crucial to all aspects of life, especially [[agriculture]], fishing, and hunting. This, in turn, helped maintain their authority and secure an advantage over rivals. In imperial times, only the rulers had the authority to announce a calendar. An illegal calendar could be considered a serious offence, often punishable by [[capital punishment]].

Early calendars were also lunisolar, but they were less stable due to their reliance on direct observation. Over time, increasingly refined methods for predicting lunar and solar cycles were developed, eventually reaching maturity around 104 BC, when the [[Taichu Calendar]] (太初曆), namely the genesis calendar, was introduced during the [[Han dynasty]]. This calendar laid the foundation for subsequent calendars, with its principles being followed by calendar experts for over two thousand years. Over centuries, the calendar was refined through advancements in astronomy and [[horology]], with dynasties introducing variations to improve accuracy and meet cultural or political needs.

Improving accuracy has its downsides. The solar terms, namely solar positions, calculated based on the predicted location of the sun, make them far more irregular than a simple average model. In practice, solar terms do not need to be maximally precise because climate does not change overnight. The introduction of the [[leap second]] to the Chinese calendar is somewhat excessive, as it makes future predictions more challenging. This is particularly true since the leap second is typically announced six months in advance, which can complicate the determination of which day the new moon or solar terms fall on, especially when they occur close to midnight.

While modern China primarily adopts the [[Gregorian calendar]] for official purposes, the traditional calendar remains culturally significant, influencing festivals and cultural practices, determining the timing of [[Chinese New Year]] with traditions like the twelve animals of the [[Chinese zodiac]] still widely observed. The [[winter solstice]] serves as another New Year, a tradition inherited from ancient China. Beyond China, it has shaped other East Asian calendars, including the [[Korean New Year|Korean]], [[Tết|Vietnamese]], and Japanese lunisolar systems, each adapting the same lunisolar principles while integrating local customs and terminology.

The sexagenary cycle, a repeating system of [[Heavenly Stems]] and [[Earthly Branches]], is used to mark years, months, and days. Before adopting their current names, the Heavenly Stems were known as the "Ten Suns" (十日),<ref>{{Cite web |title=中國哲學書電子化計劃字典 |url=https://ctext.org/dictionary.pl?if=gb&id=37017 |access-date=2025-07-18 |website=ctext.org |language=zh-TW}}</ref><ref>{{Cite web |title=中國哲學書電子化計劃字典 |url=https://ctext.org/dictionary.pl?if=gb&id=281075 |access-date=2025-07-18 |website=ctext.org |language=zh-TW}}</ref> having research that it is a remnant of an ancient [[solar calendar]].<ref>{{Cite web |title=_彝学研究网 |url=http://www.yixueyanjiu.com/details.jsp?class=8&id=32483 |access-date=2025-07-18 |website=www.yixueyanjiu.com}}</ref> 

[[Epoch]]s, or fixed starting points for year counting, have played an essential role in the Chinese calendar's structure. Some epochs are based on historical figures, such as the inauguration of the Yellow Emperor ([[Yellow Emperor|Huangdi]]), while others marked the rise of dynasties or significant political shifts. This system allowed for the numbering of years based on regnal eras, with the start of a ruler's reign often resetting the count.

The Chinese calendar also tracks time in smaller units, including months, days, double-hour, hour and quarter periods. These timekeeping methods have influenced broader fields of horology, with some principles, such as precise time subdivisions, still evident in modern scientific timekeeping. The continued use of the calendar today highlights its enduring cultural, historical, and scientific significance.

==Etymology==
[[File:秝-oracle.svg|thumb|Ancient form 秝 in oracle bone script]]
The name of calendar is in {{lang-zh|c=曆|p=lì}}, and was represented in earlier character forms variants ({{lang|zh|歷, 厤}}), and ultimately derived from an ancient form ({{lang|zh|秝}}). The ancient form of the character consists of two stalks of rice plant ({{lang|zh|禾}}), arranged in parallel. This character represents the order in space and also the order in time.<ref>{{Cite web |script-title=zh:秝 |url=https://humanum.arts.cuhk.edu.hk/Lexis/lexi-mf/search.php?word=%E7%A7%9D |website={{lang|zh|漢語多功能字庫}}}}</ref> As its meaning became complex, the modern dedicated character ({{lang|zh|曆}}) was created to represent the meaning of calendar.

Maintaining the correctness of calendars was an important task to maintain the authority of rulers, being perceived as a way to measure the ability of a ruler. For example, someone seen as a competent ruler would foresee the coming of seasons and prepare accordingly. This understanding was also relevant in predicting abnormalities of the Earth and [[Astronomical object|celestial bodies]], such as lunar and solar [[eclipse]]s. The significant relationship between authority and timekeeping helps to explain why there are 102 calendars in Chinese history, trying to predict the correct courses of sun, moon and stars, and marking good time and bad time. Each calendar is named as {{lang|zh|＿＿曆}} and recorded in a dedicated calendar section in history books of different eras. The last one in imperial era was {{lang|zh|時憲曆}}. A ruler would issue an [[almanac]] before the commencement of each year.  There were private almanac issuers, usually illegal, when a ruler lost his control of some territories.

There are various Chinese terms for the calendar including:

* Nongli Calendar ({{lang-zh|links=yes|t=農曆|s=农历|p=nónglì|l=agricultural calendar}})
* Jiuli Calendar ({{lang-zh|links=yes|t=舊曆|s=旧历|p=jiùlì|j=Gau6 Lik6|l=former calendar}})
* Laoli Calendar ({{lang-zh|links=yes|t=老曆|s=老历|p=lǎolì|l=old calendar}})
* Zhongli Calendar ({{lang-zh|links=yes|t=中曆|s=中历|p=zhōnglì|j=zung1 lik6|l=Chinese calendar}})
* Huali Calendar ({{lang-zh|links=yes|t=華曆|s=华历|p=huálì|j=waa4 lik6|l=Chinese calendar}}) [[File:Chinese Calendar of 2017.png|thumb|alt=See caption|2017 Chinese calendar]]

[[File:Chinese Calendar(Daoguang 15).jpg|thumb|alt=Handwritten calendar|Page of a Chinese calendar containing monthly information in the years [[Daoguang]] 14–16, corresponding to 1834–1836]]

Various modern Chinese calendar names resulted from the struggle between the introduction of Gregorian calendar by government and the preservation of customs by the public in the era of [[Republic of China (1912–1949)|Republic of China]].<ref>{{cite journal |author1=朱文哲 |script-title=zh:西曆·國曆·公曆——近代中國的曆法"正名" |script-journal=zh:史林 |date=2019 |volume=6 |url=http://www.qvip.net/article-9896 |access-date=2023-01-27 |archive-date=2023-01-27 |archive-url=https://web.archive.org/web/20230127145432/http://www.qvip.net/article-9896 |url-status=live }}</ref> The government wanted to abolish the Chinese calendar to force everyone to use the Gregorian calendar, and even abolished the Chinese New Year, but faced great opposition.  The public needed the astronomical Chinese calendar to do things at a proper time, for example farming and fishing; also, a wide spectrum of festivals and customs observations have been based on the calendar.  The government finally compromised and rebranded it as the agricultural calendar in 1947,<ref>{{cite web |script-title=zh:中華民國三十六年標準農曆通書 |url=https://taiwanebook.ncl.edu.tw/zh-tw/book/NCL-9910008216 |access-date=2023-01-27 |archive-date=2023-01-27 |archive-url=https://web.archive.org/web/20230127142624/https://taiwanebook.ncl.edu.tw/zh-tw/book/NCL-9910008216 |url-status=live }}</ref> depreciating the calendar to merely agricultural use.

{| class="wikitable"
|+ Some modern names of Chinese calendar and Gregorian calendar
! Chinese calendar !! Gregorian calendar
|-
| {{lang|zh|唐曆, 華曆,}} Chinese calendar|| {{lang|zh|西洋曆, 洋曆, 西曆}}, Western calendar
|-
| {{lang|zh|舊曆, 老曆, 古曆}}, old calendar || {{lang|zh|新曆}}, new calendar
|-
| {{lang|zh|陰曆}}, yin calendar || {{lang|zh|陽曆}}, yang calendar
|-
| {{lang|zh|傳統曆}}, traditional calendar ||
|-
| {{lang|zh|農曆, 農民曆}}, agricultural calendar ||
|-
| {{lang|zh|夏曆}}, The first dynasty calendar ||
|-
| {{lang|zh|黄曆, 黄帝曆}}, Yellow Emperor calendar || 
|-
| || {{lang|zh|公曆}}, public calendar, namely universal calendar or common calendar
|-
| || {{lang|zh|國曆}}, national calendar
|-
| {{lang|zh|皇曆}}, Imperial calendar (obsoleted)
|-
|}

After the end of the imperial era, there are some almanacs based upon the [[algorithm]] of the last Imperial calendar with longitude of [[Peking]].  Such almanacs were under the name of "universal book" {{lang|zh|通書}}, or under Cantonese name {{lang|yue|通勝}}, transcribed as [[Tung Shing]].  Later these almanacs moved to a new calculation based on the location of [[Purple Mountain Observatory]], with a longitude of 120°E.

== Year-numbering systems ==
===Eras===
{{Main|Chinese era name}}
Ancient China numbered years from an emperor's ascension to the throne or his declaration of a new era name. The first recorded reign title was {{zh-no-labels|p=Jiànyuán|c=建元 |out=p}}, from 140 BCE; the last reign title was {{lang-zh|labels=no|s=宣统|t=宣統|l=|c=|p=Xuāntǒng|out=p}}, from 1908 CE. The era system was abolished in 1912, after which the current or [[Republic of China (1912–49)|Republican era]] was used.

===Epochs===
{{See also|Epoch}}
{{Further|Chinese era name|Regnal year}}
An epoch is a point in time chosen as the origin of a particular [[calendar era]], thus serving as a reference point from which subsequent time or dates are measured. The use of epochs in Chinese calendar system allow for a chronological starting point from whence to begin point continuously numbering subsequent dates. Various epochs have been used. Similarly, nomenclature similar to that of the Christian era has occasionally been used:<ref>{{cite journal |author=Liu |first=Rong |year=2004 |trans-title=Subsidiary Relations in the Pre-Qin Period |script-title=zh:春秋依附关系探讨 |url=https://caod.oriprobe.com/articles/7940438/Subsidiary_Relations_in_the_Pre_Qin_Period.htm |journal=辽宁大学学报：哲社版 Journal of Liaoning University: Philosophy and Social Science Edition |volume=32 |issue=6 |pages=43–50 |access-date=2 May 2023 |archive-date=27 April 2023 |archive-url=https://web.archive.org/web/20230427153827/https://caod.oriprobe.com/articles/7940438/Subsidiary_Relations_in_the_Pre_Qin_Period.htm |url-status=live }}</ref>
{| class="wikitable"
!Era
!Chinese name
!Start
!Year 1
!{{CURRENTYEAR}} CE is year...
|-
|Yellow Emperor (Huángdì) year
|{{lang|zh-hant|黄帝紀年}}
|[[Yellow Emperor]] (YE) began reigning
|2697 BCE or 2698 BCE
|{{#expr:{{CURRENTYEAR}}+2697}} or {{#expr:{{CURRENTYEAR}}+2698}}
|-
|Yáo year
|{{lang|zh-hant|唐堯紀年}}
|[[Emperor Yao]] began reigning
|2156 BCE
|{{#expr:{{CURRENTYEAR}}+2156}}
|-
|Gònghé year
|{{lang|zh-hant|共和紀年}}
|[[Gonghe Regency]] began
|841 BCE
|{{#expr:{{CURRENTYEAR}}+841}}
|-
|Confucius year
|{{lang|zh-hant|孔子紀年}}
|[[Confucius]]'s birth year
|551 BCE
|{{#expr:{{CURRENTYEAR}}+551}}
|-
|Unity year
|{{lang|zh-hant|統一紀年}}
|[[Qin Shi Huang]] completes unification
|221 BCE
|{{#expr:{{CURRENTYEAR}}+221}}
|}
No reference date is universally accepted. The most popular is the Gregorian calendar ({{lang-zh|labels=no|p=gōnglì|t={{linktext|公曆}}|s={{linktext|公历}}|l=common calendar}}).

During the 17th century, the [[Jesuit China missions|Jesuit missionaries]] tried to determine the [[Epoch (reference date)|epochal year]] of the Chinese calendar. In his {{lang|la|Sinicae historiae decas prima}} (published in [[Munich]] in 1658), [[Martino Martini]] (1614–1661) dated the [[Yellow Emperor]]'s ascension at 2697 BCE and began the Chinese calendar with the reign of [[Fuxi]] (which, according to Martini, began in 2952 BCE).
[[Philippe Couplet]]'s 1686 ''Chronological table of Chinese monarchs'' ({{lang|la|Tabula chronologica monarchiae sinicae}}) gave the same date for the Yellow Emperor. The Jesuits' dates provoked interest in Europe, where they were used for comparison with Biblical chronology.{{citation needed |date=October 2018}} Modern Chinese chronology has generally accepted Martini's dates, except that it usually places the reign of the Yellow Emperor at 2698 BCE and omits his predecessors Fuxi and [[Shennong]] as "too legendary to include".{{Quote without source|date=October 2018}}

Publications began using the estimated birth date of the [[Yellow Emperor]] as the first year of the Han calendar in 1903, with newspapers and magazines proposing different dates. [[Jiangsu]] province counted 1905 as the year 4396 (using a year 1 of 2491 BCE, and implying that {{CURRENTYEAR}} CE is {{#expr:{{CURRENTYEAR}}+2491}}), and the newspaper ''[[Ming Pao]]'' ({{lang-zh|labels=no|t=明報}}) reckoned 1905 as 4603 (using a year 1 of 2698 BCE, and implying that {{CURRENTYEAR}} CE is {{#expr:{{CURRENTYEAR}}+2698}}).{{citation needed |date=October 2018}} [[Liu Shipei]] ({{lang|zh|劉師培}}, 1884–1919) created the [[Yellow Emperor Calendar]] ({{lang|zh|黃帝紀元, 黃帝曆 or 軒轅紀年}}), with year 1 as the birth of the emperor (which he determined as 2711 BCE, implying that {{CURRENTYEAR}} CE is {{#expr:{{CURRENTYEAR}}+2711}}).<ref>{{Cite web |date=2020-08-01 |title=The Origin of the Yellow Emperor Era Chronology |url=https://www2.ihp.sinica.edu.tw/file/1097kaBVwNb.pdf |archive-url=https://web.archive.org/web/20200801082232/https://www2.ihp.sinica.edu.tw/file/1097kaBVwNb.pdf |archive-date=1 August 2020 |access-date=2023-05-02}}</ref> There is no evidence that this calendar was used before the 20th century.{{sfnb|Cohen|2012| p = 1, 4}} Liu calculated that the 1900 international expedition sent by the [[Eight-Nation Alliance]] to suppress the [[Boxer Rebellion]] entered Beijing in the 4611th year of the Yellow Emperor.

[[Taoists]] later adopted the [[Yellow Emperor Calendar]] and named it [[Tao Calendar]] ({{lang|zh|道曆}}).

On 2 January 1912, [[Sun Yat-sen]] announced changes to the official calendar and era. 1 January was {{tlit|zh|pinyin|Huángdì}} year 4809.11.14, assuming a year 1 of 2698 BCE, making {{CURRENTYEAR}} CE year {{#expr:{{CURRENTYEAR}}+2698}}. Many [[overseas Chinese]] communities like [[Chinatown, San Francisco|San Francisco's Chinatown]] adopted the change.{{sfnp|Aslaksen|2010}}

The modern Chinese standard calendar uses the epoch of the Gregorian calendar, which is on 1 January of the year 1 CE.

==History==
The Chinese calendar system has a long history, which has traditionally been associated with specific [[Dynasties of China|dynastic periods]]. Various individual calendar types have been developed with different names. In terms of historical development, some of the calendar variations are associated with dynastic changes along a spectrum beginning with a prehistorical/mythological time to and through well attested historical dynastic periods. Many individuals have been associated with the development of the Chinese calendar, including researchers into underlying astronomy; and, furthermore, the development of instruments of observation are historically important. Influences from India, Islam, and Jesuits also became significant.

===Solar calendars===
[[File:Five Phases and Four Seasons Calendar.png|thumb|alt=See caption|Five-phase and four-quarter calendars]]
The traditional Chinese lunisolar calendar was developed between 771 BCE and 476 BCE, during the [[Spring and Autumn period]] of the [[Eastern Zhou]] dynasty. Solar calendars were used before the [[Zhou dynasty]] period, along with the basic sexagenary system.

One version of the solar calendar is the five-elements (or phases) calendar ({{zh-no-labels|s=五行历|t=五行曆|p=wǔxíng lì}}), which derives from the [[Wuxing (Chinese philosophy)|Wu Xing]]. A 365-day year was divided into five phases of 72 days, with each phase preceded by an [[Intercalation (timekeeping)|intercalary]] day associated with the claimed beginning of the following 72 day period of domination by the next Wu Xing element; thus, the five phases each begin with a governing-element day ({{lang|zh|行御}}), followed by a 72-day period characterized by the ruling element. Years began on a {{zh-no-labels|p=jiǎzǐ|c=甲子|out=p}} day and a 72-day wood phase, followed by a {{zh-no-labels|c=丙子|p=bǐngzǐ|out=p}} day and a 72-day fire phase; a {{zh-no-labels|p=wùzǐ|c=戊子|out=p}} day and a 72-day earth phase; a {{zh-no-labels|p=gēngzǐ|c=庚子|out=p}} day and a 72-day metal phase, and a {{zh-no-labels|p=rénzǐ|c=壬子|out=p}} day followed by a water phase.<ref name="Guanzi 41">{{cite wikisource |title=zh:管子|trans-title=[[Guanzi (text)|Guanzi]] |chapter=第41篇五行|trans-chapter=Chapter 41: Five Elements|wslanguage=zh}}</ref> Each phase consisted of two three-week months, making each year ten months long. Other days were tracked using the [[Yellow River Map]] (''He Tu'').

Another version is a four-quarters calendar ({{lang-zh|labels=no|s=四时八节历|t=四時八節曆|l=four-season eight-solar-term calendar|p=sìshí bājié lì}}, or {{lang-zh|labels=no|t=四分曆|s=四分历|p=sìfēn lì|l=quarters calendar}}). The weeks were ten days long, with one month consisting of three weeks. A year had 12 months, with a ten-day week [[Intercalation (timekeeping)|intercalated]] in summer as needed to keep up with the tropical year. The 10 [[Heavenly Stems]] and 12 [[Earthly Branches]] were used to mark days.<ref name="Guanzi 40">{{cite wikisource |title=管子|trans-title=[[Guanzi (text)|Guanzi]] |chapter=第40篇四時|trans-chapter=Chapter 40: Four Sections|wslanguage=zh}}</ref>

A third version is the balanced calendar ({{lang-zh|labels=no|t=調曆|s=调历 |p=tiáo lì}}). A year was 365.25 days, and a month was 29.5 days. After every 16th month, a half-month was intercalated. According to [[oracle bone]] records, the [[Shang dynasty]] calendar ({{Circa|1600|1046}} BCE) was a balanced calendar with 12 to 14 months in a year; the month after the winter solstice was {{tlit|zh|pinyin|Zhēngyuè}}.<ref>{{cite web |url=http://www.newsmth.net/bbsanc.php?path=/groups/sci.faq/Astronomy/bw/all2/bk37k/M.1275291864.z0&ap=353 |script-title=zh:中国农历发展简史 |trans-title=A brief history of the development of Chinese Lunar calendar |format=PDF |access-date=24 February 2016 |archive-date=26 February 2021 |archive-url=https://web.archive.org/web/20210226064642/https://www.newsmth.net/bbsanc.php?path=%2Fgroups%2Fsci.faq%2FAstronomy%2Fbw%2Fall2%2Fbk37k%2FM.1275291864.z0&ap=353 |url-status=dead }}</ref>

A solar calendar called the [[Tung Shing]], the ''Yellow Calendar'' or  ''Imperial Calendar'' (both alluding to [[Yellow Emperor]]) continued to see use as an almanac and agricultural guide throughout Chinese history.<ref>{{cite book |first=Martin |last=Palmer |title=T'ung Shu: the Ancient Chinese Almanac |publisher=Shambhala |location=Boston |year=1986 |isbn=9780394742212 |pages=9–10}}</ref>

===Lunisolar calendars by dynasty===
{{See also|Lunisolar calendar}}
Lunisolar calendars involve correlations of the cycles of the sun (solar) and the moon (lunar).

====Zhou dynasty====
The first [[Lunisolar calendar|lunisolar]] calendar was the ''Zhou'' calendar ({{lang-zh|labels=no|t=周曆|s=周历}}), introduced under the [[Zhou dynasty]] (1046 BCE – 256 BCE). This calendar sets the beginning of the year at the day of the new moon before the winter solstice.

====Competing Warring states calendars====
{{See also|Warring States period}}
Several competing [[Lunisolar calendar|lunisolar]] calendars were introduced as Zhou devolved into the Warring States, especially by states fighting Zhou control during the [[Warring States period]] (perhaps 475 BCE – 221 BCE).
From the [[Warring States period]] (ending in 221 BCE), six especially significant calendar systems are known to have begun to be developed. Later on, during their future course in history, the modern names for the ancient six calendars were also developed: ''Huangdi, Yin, Zhou, Xia, Zhuanxu,'' and ''Lu''.<ref>[https://ytliu0.github.io/ChineseCalendar/guliuli.html Yuk Tung Liu, 2018–2024, at GitHub]</ref>

Modern historical knowledge and records are limited for the earlier calendars. These calendars are known as the ''six ancient calendars'' ({{lang-zh|labels=no|t=古六曆|s=古六历}}), or quarter-remainder calendars, ({{lang-zh|labels=no|t=四分曆|s=四分历|p=sìfēnlì}}), since all calculate a year as {{frac|365|1|4}} days long. Months begin on the day of the new moon, and a year has 12 or 13 months. Intercalary months (a 13th month) are added to the end of the year.

{{anchor|Lu calendar}}
The state of [[Lu (state)|Lu]] issued its own ''Lu calendar'' ({{lang-zh|labels=no|t=魯曆|s=鲁历}}).

{{anchor|Xia calendar}}
The state of [[Jin (Chinese state)|Jin]] issued the ''[[Xia dynasty|Xia]] calendar'' ({{lang-zh|labels=no|t=夏曆|s=夏历}})<ref name="Petersen">{{cite journal |last=Petersen |first=Jens Østergård |year=1992 |title=The Taiping Jing and the AD 102 Clepsydra Reform |journal=Acta Orientalia |volume=53 |pages=122–158 |url=https://www.academia.edu/12945035 |access-date=2 October 2018 |archive-date=11 January 2022 |archive-url=https://web.archive.org/web/20220111191102/https://www.academia.edu/12945035 |url-status=live }}</ref> with a year beginning on the day of the new moon nearest the [[March equinox]].

{{anchor|Zhuanxu calendar}}
The state of [[Qin (state)|Qin]] issued the ''[[Zhuanxu]] calendar'' ({{lang-zh|labels=no|t=顓頊曆|s=颛顼历}}), with a year beginning on the day of the new moon nearest the [[winter solstice]]. 
{{anchor|Qiang calendar|Dai calendar}}
The ''Qiang'' and ''Dai calendars'' are modern versions of the Zhuanxu calendar, used by highland peoples.

{{anchor|Yin calendar}}
The [[Song (state)|Song state]]'s ''[[Shang dynasty|Yin]] calendar'' ({{lang-zh|labels=no|t=殷曆|s=殷历}}) began its year on the day of the new moon after the winter solstice.

====Qin and early Han dynasties====
{{See also|Qin dynasty|Han dynasty}}
{{anchor|Qin calendar}}
After [[Qin Shi Huang]] unified China under the Qin dynasty in 221 BCE, the ''Qin calendar'' ({{lang-zh|labels=no|t=秦曆|s=秦历}}) was introduced. It followed most of the rules governing the [[#Zhuanxu calendar|Zhuanxu calendar]], but the month order was that of the [[#Xia calendar|Xia calendar]]; the year began with month 10 and ended with month 9, analogous to a Gregorian calendar beginning in October and ending in September. The intercalary month, known as ''the second'' {{lang-zh|labels=no|t=後九月|s=后九月|p=Jiǔyuè|out=p}}, was placed at the end of the year. The Qin calendar was used going into the Han dynasty.

====Han dynasty Tàichū calendar====
{{Further|Han dynasty|Emperor Wu of Han#Calendar reform}}
{{anchor|Tàichū calendar|Taichu calendar}}
[[Emperor Wu of Han]] {{reign|141|87 BCE}} introduced reforms in the seventh of the eleven named eras of his reign, {{lang-zh|labels=no|t=太初|s=太初|p=Tàichū|l=Grand Beginning|out=p}}, 104 BCE – 101 BCE. His ''{{tlit|zh|pinyin|Tàichū}} calendar'' ({{lang-zh|labels=no|t=太初曆|s=太初历|l=grand beginning calendar}}) defined a solar year as {{frac|365|385|1539}} days (365;06:00:14.035), and the lunisolar month had {{frac|29|43|81}} days (29;12:44:44.444). 
Since <math>\left(365+\frac{385}{1539}\right)\times19=\left(29+\frac{43}{81}\right)\times \left(19\times 12 + 7 \right)
 </math>, the 19-year cycle used for the 7 additional months was taken as exact, and not as an approximation.

This calendar introduced the 24 [[solar term]]s, dividing the year into 24 equal parts of 15° each. Solar terms were paired, with the 12 combined periods known as ''climate terms''. The first solar term of the period was known as a pre-climate ({{Lang-zh|s=节气|t=節氣|labels=no}}), and the second was a mid-climate ({{Lang-zh|s=中气|t=中氣|labels=no}}). Months were named for the mid-climate to which they were closest, and a month without a mid-climate was an intercalary month.<ref>{{Cite web |title=Chinese calendar {{!}} Lunar Year, Solar Eclipses & Solstices {{!}} Britannica |url=https://www.britannica.com/science/Chinese-calendar |access-date=2024-06-23 |website=www.britannica.com |language=en}}</ref>

The Taichu calendar established a framework for traditional calendars, with later calendars adding to the basic formula.

====Northern and Southern Dynasties Dàmíng calendar====
{{See also|Northern and Southern dynasties#Southern dynasties}}
{{anchor|Dàmíng calendar|Daming calendar}}
The ''Dàmíng calendar'' ({{lang-zh|labels=no|t=大明曆|s=大明历|l=brightest calendar}}), created in the [[Northern and Southern Dynasties]] by [[Zu Chongzhi]] (429 CE – 500 CE), introduced the equinoxes.

====Tang dynasty Wùyín Yuán calendar====
{{See also|Tang dynasty}}{{Further|Syzygy (astronomy)}}
{{anchor|Wùyín Yuán calendar|Wuyin Yuan calendar}}
The use of [[Syzygy (astronomy)|syzygy]] to determine the lunisolar month was first described in the [[Tang dynasty]] ''{{tlit|zh|pinyin|Wùyín Yuán}} calendar'' ({{lang-zh|labels=no|t=戊寅元曆|s=戊寅元历|l=earth tiger epoch calendar}}).

====Yuan dynasty Shòushí calendar====
{{See also|Yuan dynasty}}
{{anchor|Shòushí calendar|Shoushi calendar}}
The [[Yuan dynasty]] ''Shòushí calendar'' ({{lang-zh|labels=no|t=授時曆|s=授时历|l=season granting calendar}}) used [[spherical trigonometry]] to find the length of the [[tropical year]].<ref>{{Cite book|last=Needham |first=Joseph |orig-year=1954 |title=Science and Civilization in China: Volume 3, Mathematics and the Sciences of the Heavens and the Earth |volume=3 |date=1986 |pages=109–110|bibcode=1959scc3.book.....N }}</ref><ref>{{cite book |last=Ho |first=Peng Yoke |date=2000 |title=Li, Qi, and Shu: An Introduction to Science and Civilization in China |location=Mineola |publisher=Dover Publications |isbn=978-0-486-41445-4 |page=105}}</ref><ref>{{cite book |last=Restivo |first=Sal |date=1992 |title=Mathematics in Society and History: Sociological Inquiries |location=Dordrecht |publisher=Kluwer Academic Publishers |isbn=978-1-4020-0039-3 |page=32}}</ref>
The calendar had a 365.2425-day year, identical to the [[Gregorian calendar]].<ref>{{cite book |editor=Asiapac Editorial |date=2004 |title=Origins of Chinese Science and Technology |translator1=Yang Liping |translator2=Y.N. Han |location=Singapore |publisher=Asiapac Books |isbn=978-981-229-376-3 |page=132}}</ref>

==== Ming and Qing Shíxiàn calendar ====
{{Main|Chongzhen calendar}}
{{anchor|Shíxiàn calendar|Shixian calendar|Chongzhen calendar}}
From 1645 to 1913 the ''{{tlit|zh|pinyin|Shíxiàn}}'' or ''Chongzhen calendar'' was developed. During the late [[Ming dynasty]], the Chinese Emperor appointed [[Xu Guangqi]] in 1629 to be the leader of the [[Chongzhen calendar|Shixian calendar]] reform. Assisted by Jesuits, he translated Western astronomical works and introduced new concepts, such as those of [[Nicolaus Copernicus]], [[Johannes Kepler]], [[Galileo Galilei]], and [[Tycho Brahe]]; however, the new calendar was not released before the end of the dynasty.

In the early [[Qing dynasty]], [[Johann Adam Schall von Bell]] submitted the calendar which was edited by the lead of [[Xu Guangqi]] to the [[Shunzhi Emperor]].<ref>{{cite journal |last1=Stone |first1=Richard |title=Scientists Fete China's Supreme Polymath |journal=Science |date=2 November 2007 |volume=318 |issue=5851 |pages=733 |doi=10.1126/science.318.5851.733 |pmid=17975042 |s2cid=162156995 |doi-access=free }}</ref> 
The Qing government issued it as the ''{{tlit|zh|pinyin|Shíxiàn}} (seasonal) calendar''. In this calendar, the [[solar term]]s are 15° each along the [[ecliptic]] and it can be used as a [[solar calendar]]. However, the length of the climate term near the [[Apsis|perihelion]] is less than 30 days and there may be two mid-climate terms. The {{tlit|zh|pinyin|Shíxiàn}} calendar changed the mid-climate-term rule to "decide the month in sequence, except the intercalary month."<ref>{{Cite web |script-title=zh:本世纪仅有4次！闰二月为何少见？-新华网 |url=http://www.news.cn/tech/2023-03/21/c_1129450471.htm |access-date=2023-05-02 |website=www.news.cn |archive-date=2 May 2023 |archive-url=https://web.archive.org/web/20230502045811/http://www.news.cn/tech/2023-03/21/c_1129450471.htm |url-status=live }}</ref>

The present "traditional calendar" follows the Shíxiàn calendar, except:
# The baseline is Chinese Standard Time, rather than Beijing local time.
# Modern astronomical data, rather than mathematical calculations, is used.

====Modern Chinese calendar====

Despite the Chinese calendar losing its place as the country's official calendar at the beginning of the 20th century,<ref name="Sun Yat-sen">{{cite book |author=Sun Yat-sen |url=https://confuciusinstitute.unl.edu/Week%205.2%20-%20Sun%20Yat-sen%20-%20Inaugural%20Address%20of%20the%20Provisional%20President%28January%201%2C%201912%29.pdf |title= |date=1982 |publisher={{lang|zh|中华书局}} |volume=v. 2 |location=Beijing |page=5 |script-title=zh:孙中山全集 |trans-title=The Complete Works of Sun Yat-sen |script-chapter=zh:临时大总统改历改元通电 |trans-chapter=Provisional President's open telegram on calendar change and era change |access-date=2 May 2023 |orig-year=Telegram originally sent 1 January 1912 |archive-url=https://web.archive.org/web/20230129194502/https://confuciusinstitute.unl.edu/Week%205.2%20-%20Sun%20Yat-sen%20-%20Inaugural%20Address%20of%20the%20Provisional%20President%28January%201%2C%201912%29.pdf |archive-date=29 January 2023 |url-status=live}}</ref> its use has continued.

{{anchor|Republic of China Calendar}}
The ''Republic of China Calendar'' published by the [[Beiyang government]] of the Republic of China still listed the dates of the Chinese calendar in addition to the Gregorian calendar.

{{anchor|Kuómín calendar|Kuomin calendar}}
In 1929, the [[Nationalist government]] tried to ban the traditional Chinese calendar. The ''{{tlit|zh|pinyin|Kuómín}} Calendar'' published by the government no longer listed the dates of the Chinese calendar. 
However, Chinese people were used to the traditional calendar, and many traditional customs were based on the Chinese calendar. The ban failed and was lifted in 1934.<ref>{{Cite web |title=Rules for the Chinese Calendar |url=https://ytliu0.github.io/ChineseCalendar/rules.html |url-status=live |archive-url=https://web.archive.org/web/20230220003057/https://ytliu0.github.io/ChineseCalendar/rules.html |archive-date=20 February 2023 |access-date=2023-02-20 |website=ytliu0.github.io}}</ref>

{{anchor|Wànniánlì calendar|Wannianli calendar}}
The latest Chinese calendar was "New Edition of {{tlit|zh|pinyin|Wànniánlì}}, revised edition", edited by Beijing Purple Mountain Observatory, People's Republic of China.<ref>{{Cite book |last=CAS |first=Purple Mountain Observatory |title=New Edition of Wànniánlì, revised edition |publisher=Popular Science Press |year=1986}}</ref>

In China, the modern calendar is defined by the [[National Standards of the People's Republic of China|Chinese national standard]] GB/T 33661–2017,<ref>{{Cite web |script-title=zh:国家标准 {{!}} GB/T 33661-2017 |url=http://c.gb688.cn/bzgk/gb/showGb?type=online&hcno=E107EA4DE9725EDF819F33C60A44B296 |access-date=28 September 2023 |archive-date=28 September 2023 |archive-url=https://web.archive.org/web/20230928111539/http://c.gb688.cn/bzgk/gb/showGb?type=online&hcno=E107EA4DE9725EDF819F33C60A44B296 |url-status=live }}</ref> "Calculation and Promulgation of the Chinese Calendar", issued by the [[Standardization Administration of China]] on 12 May 2017.

Although modern-day China uses the [[Gregorian calendar]], the traditional Chinese calendar governs holidays, such as the [[Chinese New Year]] and [[Lantern Festival]], in both China and [[overseas Chinese]] communities. It also provides the traditional Chinese nomenclature of dates within a year which people use to select auspicious days for [[Auspicious wedding dates|weddings]], funerals, moving or starting a business.<ref>{{Cite journal |last1=Xiao |first1=Fang |last2=Zhang |first2=Juwen |last3=Long |first3=Bill |date=2017 |title=The Predicament, Revitalization, and Future of Traditional Chinese Festivals |jstor=44790971 |journal=Western Folklore |volume=76 |issue=2 |pages=181–196 }}</ref> The evening state-run news program ''[[Xinwen Lianbo]]'' in the [[People's Republic of China]] continues to announce the months and dates in both the Gregorian and the traditional lunisolar calendar.

To optimize the Chinese calendar, astronomers have proposed a number of changes. [[Kao Ping-tse]] ({{lang-zh|labels=no|c=高平子}}; 1888–1970), a Chinese astronomer who co-founded the [[Purple Mountain Observatory]], proposed that month numbers be calculated before the new moon and solar terms to be rounded to the day. Since the intercalary month is determined by the first month without a mid-climate and the mid-climate time varies by time zone, countries that adopted the calendar but calculate with their own time could vary from the time in China.<ref>{{Cite book |last=Martzloff |first=Jean-Claude |url=https://books.google.com/books?id=SYj2DAAAQBAJ&dq=Gao+Pingzi+month+numbers&pg=PA242 |title=Astronomy and Calendars – The Other Chinese Mathematics: 104 BCE – 1644 CE |date=2016-09-01 |publisher=Springer |isbn=978-3-662-49718-0 |language=en |access-date=19 October 2022 |archive-date=8 October 2023 |archive-url=https://web.archive.org/web/20231008220827/https://books.google.com/books?id=SYj2DAAAQBAJ&dq=Gao+Pingzi+month+numbers&pg=PA242 |url-status=live }}</ref>

===Contributions from Chinese astronomy===
{{Main|Chinese astronomy}}

The Chinese calendar has been a development involving much observation and calculation of the apparent movements of the Sun, Moon, planets, and stars, as observed from Earth.

Many Chinese astronomers have contributed to the development of the Chinese calendar. Many were of the scholarly or ''shi'' class ({{lang-zh |t = 士|s =士|p=shì}}), including writers of history, such as [[Sima Qian]].

Notable Chinese astronomers who have contributed to the development of the calendar include [[Gan De]], [[Shi Shen]], and [[Zu Chongzhi]]

{{further|Chinese star maps|Armillary sphere}}
Early technological developments aiding in calendar development include the development of the [[gnomon]].  Later technological developments useful to the calendar system include [[Chinese star names|naming, numbering]] and mapping of the sky, the development of analog computational devices such as the armillary sphere and the water clock, and the establishment of observatories.

==Phenology==
{{Main|Phenology}}
Early calendar systems, including the Chinese calendar, often were closely tied to natural phenomena. [[Phenology]] is the study of periodic events in [[biological life cycle]]s and how these are influenced by [[seasonality|seasonal]] and interannual variations in [[climate]], as well as [[environmental factor|habitat factors]] (such as [[elevation]]).<ref>{{Cite web|url=https://www.merriam-webster.com/dictionary/phenology|title=Phenology|date=2020|website=Merriam-Webster}}</ref> The [[East Asian rainy season|plum-rains season]] ({{linktext|梅雨|lang=zh}}), the rainy season in late spring and early summer, begins on the first {{tlit|zh|pinyin|bǐng}} day after ''[[Mangzhong]]'' ({{lang|zh-hant|芒種}}) and ends on the first {{tlit|zh|pinyin|wèi}} day after [[Xiaoshu]] ({{lang|zh|小暑}}). The [[dog days|Three Fu]] ({{lang-zh|labels=no|c={{linktext|三伏}}|p=sānfú}}) are three periods of hot weather, counted from the first {{tlit|zh|pinyin|gēng}} day after the summer solstice. The first {{tlit|zh|pinyin|fu}} ({{lang-zh|labels=no|c=初伏|p=chūfú}}) is 10 days long. The mid-{{tlit|zh|pinyin|fu}} ({{lang-zh|labels=no|c=中伏|p=zhōngfú}}) is 10 or 20 days long. The last {{tlit|zh|pinyin|fu}} ({{lang-zh|labels=no|c=末伏|p=mòfú}}) is 10 days from the first {{tlit|zh|pinyin|gēng}} day after the beginning of autumn.<ref name="3 fu" /> The Shujiu cold days ({{lang-zh|labels=no|p=shǔjǐu|c=數九|l=counting to nine}}) are the 81 days after the winter solstice (divided into nine sets of nine days), and are considered the coldest days of the year. Each nine-day unit is known by its order in the set, followed by "nine" ({{lang|zh|九}}).<ref>{{Cite web |author=孙蕾 |script-title=zh:都说数九寒冬，可你知道"数九"怎么"数"？-新华网 |url=http://m.xinhuanet.com/js/2017-12/22/c_1122150122.htm |access-date=2023-05-02 |website=m.xinhuanet.com |archive-date=30 April 2023 |archive-url=https://web.archive.org/web/20230430180426/http://m.xinhuanet.com/js/2017-12/22/c_1122150122.htm |url-status=live }}</ref> In traditional [[Chinese culture]], "nine" represents the infinity, which is also the number of "Yang". According to one belief nine times accumulation of "Yang" gradually reduces the "Yin", and finally the weather becomes warm.<ref>{{Cite web |script-title=zh:五九六九沿河看柳……"数九"知识你知道多少？-新华网 |url=http://www.xinhuanet.com/politics/2018-02/26/c_1122452100.htm |access-date=2023-05-02 |website=www.xinhuanet.com |archive-date=1 May 2023 |archive-url=https://web.archive.org/web/20230501113343/http://www.xinhuanet.com/politics/2018-02/26/c_1122452100.htm |url-status=live }}</ref>

=== Names of months ===
Lunisolar months were originally named according to natural phenomena. Current naming conventions use numbers as the month names. Every month is also associated with one of the twelve [[Earthly Branches]].
{| class="wikitable"
!Month number
! Starts on Gregorian date
![[Phenology|Phenological]] name
![[Earthly Branch]] name
!Modern name
|-
|1
|between 21 January – 20 February *
|{{lang-zh |c={{linktext|陬月}} |labels=no |p=zōuyuè |l=corner month}}. square of [[Pegasus (constellation)|Pegasus]] month
|{{lang-zh |c={{linktext|寅月}} |labels=no |p=yínyuè |l=tiger month}}
|{{lang-zh |c={{linktext|正月}} |labels=no |p=zhēngyuè |l=first month}}
|-
|2
|between 20 February – 21 March *
|{{lang-zh |c={{linktext|杏月}} |labels=no|l=[[apricot]] month |p=xìngyuè}}
|{{lang-zh |c={{linktext|卯月}} |labels=no|l=rabbit month  |p=mǎoyuè}}
|{{lang-zh |c={{linktext|二月}} |labels=no|l=second month |p=èryuè}}
|-
|3
|between 21 March – 20 April *
|{{lang-zh |c={{linktext|桃月}} |labels=no |p=táoyuè |l=[[peach]] month}}
|{{lang-zh |c={{linktext|辰月}} |labels=no |p=chényuè |l=dragon month}}
|{{lang-zh |c={{linktext|三月}} |labels=no|p=sānyuè |l=third month}}
|-
|4
|between 20 April – 21 May *
|{{lang-zh |c={{linktext|梅月}} |labels=no |p=méiyuè |l=[[Prunus mume|plum]] month}}
|{{lang-zh |c={{linktext|巳月}} |labels=no |p=sìyuè |l=snake month}} 
|{{lang-zh |c={{linktext|四月}} |labels=no|p=sìyuè |l=fourth month}}
|-
|5
|between 21 May – 21 June *
|{{lang-zh |c={{linktext|榴月}} |labels=no |p=liúyuè |l=[[pomegranate]] month}}
|{{lang-zh |c={{linktext|午月}} |labels=no  |p=wǔyuè |l=horse month}}
|{{lang-zh |c={{linktext|五月}} |labels=no  |p=wǔyuè |l=fifth month}}
|-
|6
|between 21 June – 23 July *
|{{lang-zh |c={{linktext|荷月}} |labels=no |l=[[Lotus flower|lotus]] month |p=héyuè}}
|{{lang-zh |c={{linktext|未月}} |labels=no |l=goat month |p=wèiyuè}}
|{{lang-zh |c={{linktext|六月}} |labels=no |l=sixth month |p=liùyuè}}
|-
|7
|between 23 July – 23 August *
|{{lang-zh |t={{linktext|蘭月}} |s={{linktext|兰月}} |labels=no |l=[[orchid]] month |p=lányuè}}
|{{lang-zh |c={{linktext|申月}} |labels=no |l=monkey month |p=shēnyuè}}
|{{lang-zh |c={{linktext|七月}} |labels=no |l=seventh month |p=qīyuè}}
|-
|8
|between 23 August – 23 September *
|{{lang-zh |c={{linktext|桂月}} |labels=no |l=[[osmanthus]] month |p=guìyuè}}
|{{lang-zh |c={{linktext|酉月}} |labels=no |l=rooster month |p=yǒuyuè}}
|{{lang-zh |c={{linktext|八月}} |labels=no |l=eighth month |p=bāyuè}}
|-
|9
|between 23 September – 23 October *
|{{lang-zh |c={{linktext|菊月}} |labels=no |p=júyuè |l=[[chrysanthemum]] month}}
|{{lang-zh |c={{linktext|戌月}} |labels=no |l=dog month |p=xūyuè}}
|{{lang-zh |c={{linktext|九月}} |labels=no |l=ninth month |p=jiǔyuè}}
|-
|10
|between 23 October – 22 November *
|{{lang-zh |c={{linktext|露月}} |labels=no  |p=lùyuè |l=[[dew]] month}}
|{{lang-zh |c={{linktext|亥月}} |labels=no |l=pig month |p=hàiyuè}}
|{{lang-zh |c={{linktext|十月}} |labels=no |l=tenth month |p= shíyuè}}
|-
|11
|between 22 November – 22 December *
|{{lang-zh |c={{linktext|冬月}} |labels=no |p=dōngyuè |l=winter month}}; {{lang-zh |c={{linktext|葭月}} |labels=no |p=jiāyuè |l=[[Reed (plant)|reed]] month}}
|{{lang-zh |c={{linktext|子月}} |labels=no |l=rat month |p=zǐyuè}}
|{{lang-zh |c={{linktext|十一月}} |labels=no |l=eleventh month}} or {{lang-zh |c={{linktext|冬月}} |labels=no |l=eleventh month |p=dōngyuè}}
|-
|12
|between 22 December – 21 January *
|{{lang-zh |c={{linktext|冰月}} |labels=no |p=bīngyuè |l=ice month}}
|{{lang-zh |c={{linktext|丑月}} |labels=no |l=ox month |p=chǒuyuè}}
|{{lang-zh |c={{linktext|十二月}} |labels=no |l=twelfth month}} or {{lang-zh |s={{linktext|腊月}} |t={{linktext|臘月}} |labels=no |p=làyuè |l=end-of-year month}}

|}

{{asterisk}}Gregorian dates are approximate and should be used with caution. Many years have intercalary months.

Though the numbered month names are often used for the corresponding month number in the Gregorian calendar, it is important to realize that the numbered month names are not interchangeable with the Gregorian months when talking about Chinese calendar dates.

*''Incorrect'': The [[Dragon Boat Festival]] falls on 5 May in the traditional Chinese calendar, whereas the [[Double Ninth Festival]], [[Lantern Festival]], and [[Qixi Festival]] fall on 9 September, 15 January, and 7 July in the traditional Chinese calendar, respectively.
*''Correct'': The [[Dragon Boat Festival]] falls on {{tlit|zh|pinyin|Wǔyuè}} 5th in the traditional Chinese calendar, whereas the [[Double Ninth Festival]], [[Lantern Festival]] and [[Qixi Festival]] fall on {{tlit|zh|pinyin|Jiǔyuè}} 9th, {{tlit|zh|pinyin|Zhēngyuè}} 15th and {{tlit|zh|pinyin|Qīyuè}} 7th in the traditional Chinese calendar, respectively.{{efn|The Chinese or Pinyin names are not required. It is acceptable to say these dates as " 5th day of the fifth month", "9th day of the ninth month", "15th day of the first month", and "7th day of the seventh month", as long it is clear that these months are in the traditional Chinese calendar.}}
*''Alternate [[Chinese Zodiac]] correction'': The [[Dragon Boat Festival]] falls on Horse Month 5th in the traditional Chinese calendar, whereas the [[Double Ninth Festival]], [[Lantern Festival]] and [[Qixi Festival]] fall on Dog Month 9th, Tiger Month 15th and Monkey Month 7th in the traditional Chinese calendar, respectively (see [[#Sexagenary cycle|Sexagenary system]] below).

== Horology ==
{{See also|Chronometry}}
{{Further|Chinese astronomy|Chinese astrology}}

Horology, or chronometry, refers to the measurement of time. In the context of the Chinese calendar, horology involves the definition and mathematical measurement of terms or elements such observable astronomic movements or events such as are associated with days, months, years, hours, and so on. These measurements are based upon objective, observable phenomena. Calendar accuracy is based upon accuracy and precision of measurements.

The Chinese calendar is [[lunisolar calendar|lunisolar]], similar to the [[Hindu calendar|Hindu]], [[Hebrew calendar|Hebrew]] and [[Babylonian calendar|ancient Babylonian]] calendars. In this case the calendar is in part based in objective, observable phenomena and in part by mathematical analysis to correlate the observed phenomena. Lunisolar calendars especially attempt to correlate the solar and lunar cycles, but other considerations can be agricultural and seasonal or phenological, or religious, or even political.

Basic horological definitions include that days begin and end at midnight, and months begin on the day of the [[new moon]]. Years start on the second (or third) new moon after the [[winter solstice]]. [[Solar term]]s govern the beginning, middle, and end of each month. A [[sexagenary cycle]], comprising the [[heavenly stems]] ({{lang-zh|c=干|p=gān}}) and the [[earthly branches]] ({{lang-zh|c=支|p=zhī}}), is used as identification alongside each year and month, including [[Intercalation (timekeeping)|intercalary months]] or leap months. Months are also annotated as either long ({{lang-zh|c=大|l=big}} for months with 30 days) or short ({{lang-zh|c=小|l=small}} for months with 29 days). There are also other elements of the traditional Chinese calendar.

===Day===
{{See also|Day}}

Days are [[Sun]] oriented, based upon divisions of the solar year. A day ({{lang-zh|labels=no|c=日|p=rì}}) is considered both traditionally and currently to be the time from one midnight to the next. Traditionally, days (including the night-time portion) were divided into 12 double-hours, and in modern times, the 24-hour system has become more standard.

===Week===
{{For|more information on the adoption of the seven-day week|Names of the days of the week#East Asian tradition}}
{{For|more information on the ten-day week|Decan}}

As early as the Bronze Age [[Xia dynasty]], days were grouped into nine- or ten-day weeks known as {{lang-zh|labels=no|c=旬||p=xún|out=p}}.<ref>{{cite book | author = {{lang-zh|labels=no|c=海上}} | title = Zhongguo ren de sui shi wen hua | script-title = zh:中國人的歲時文化 | trans-title = Timekeeping of the Chinese culture | publisher = {{lang-zh|labels=no|c=岳麓書社}} | year = 2005 | pages = 195 | isbn = 978-7-80665-620-4 | language = zh | url = https://archive.org/details/zhongguorendesui0000hais/page/195 }}</ref> Months consisted of three {{tlit|zh|pinyin|xún}}. The first 10 days were the early {{tlit|zh|pinyin|xún}} ({{lang-zh|labels=no|c={{linktext|上旬}}}}), the middle 10 the mid {{tlit|zh|pinyin|xún}} ({{lang-zh|labels=no|c={{linktext|中旬}}}}), and the last nine (or 10) days were the late {{tlit|zh|pinyin|xún}} ({{lang-zh|labels=no|c={{linktext|下旬}}}}). Japan [[Japanese calendar#Division of the Month|adopted this pattern]], with 10-day-weeks known as {{nihongo|''jun''|旬}}. In Korea, they were known as ''sun'' ({{langx|ko|label=none|순}},{{langx|ko|label=none|旬}}).

The structure of {{tlit|zh|pinyin|xún}} led to [[Public holidays in China|public holidays]] every five or ten days. Officials of the [[Han dynasty]] were legally required to rest every five days (twice a {{tlit|zh|pinyin|xún}}, or 5–6 times a month). The name of these breaks became {{lang-zh|labels=no|t={{linktext|澣}} |s={{linktext|浣}} |l=wash |p=huàn |out=p}}.

Grouping days into sets of ten is still used today in referring to specific natural events. "Three Fu" ({{linktext|三伏|lang=zh}}), a 29–30-day period which is the hottest of the year, reflects its three-{{tlit|zh|pinyin|xún}} length.<ref name="3 fu">{{cite web |url=http://www.hko.gov.hk/prtver/html/docs/education/edu01met/wxobs/folklore/ele_hs_c.shtml |author={{lang-zh|labels=no|c=陳浩新}} |script-title=zh:「冷在三九，熱在三伏」 |trans-title=Cold is in the Three Nines, heat is in the Three Fu |website=Educational Resources – Hong Kong Observatory |language=zh  |access-date=15 May 2018 |archive-url=https://web.archive.org/web/20180615134946/http://www.hko.gov.hk/prtver/html/docs/education/edu01met/wxobs/folklore/ele_hs_c.shtml |archive-date=15 June 2018 |url-status=dead }}</ref> After the winter solstice, nine sets of nine days were counted to calculate the end of winter.<ref>{{Cite web |script-title=zh:数九从哪一天开始到哪一天结束 数九寒冬中的数九从什么时候开始 |url=https://wannianli.tianqi.com/news/281436.html |access-date=2023-05-02 |website=万年历 |archive-date=30 April 2023 |archive-url=https://web.archive.org/web/20230430033214/https://wannianli.tianqi.com/news/281436.html |url-status=live }}</ref>

==== Seven-day week and 28-day cycle ====
The seven-day week was adopted from the Hellenistic system by the 4th century CE{{Citation needed|date=September 2023}}, although its method of transmission into China is unclear. It was again transmitted to China in the 8th century by [[Manichaeism|Manichaeans]] via [[Kangju]],  spoken in a variant of [[Sogdian language]] (a Central Asian kingdom near [[Samarkand]]),<ref>{{cite web |url=http://www.cjvlang.com/Dow/dowjpn.html |website=CJVLang |title=Days of the week in Japanese |access-date=15 May 2018 |archive-date=24 December 2017 |archive-url=https://web.archive.org/web/20171224044408/http://www.cjvlang.com/Dow/dowjpn.html |url-status=live }}</ref>{{efn|The 4th-century date, according to the ''[[Cihai]]'' encyclopedia,{{year needed|date=April 2015}} is due to a reference to Fan Ning ({{lang-zh|labels=no|t={{linktext|範寧}}|s={{linktext|范宁}}}}), an astrologer of the [[Jin dynasty (265–420)|Jin dynasty]].{{Full citation needed|date=October 2018}}}}{{efn|The renewed adoption from Manichaeans by the 8th century ([[Tang dynasty]]) is documented by the writings of the Chinese Buddhist monk [[Yijing (monk)|Yi Jing]] and the Ceylonese Buddhist monk [[Amoghavajra|Bu Kong]].{{Full citation needed|date=October 2018}}}}. Its meaning is derived from the five classical planets, along with the Sun and Moon, making a total of seven celestial bodies highly visible in the sky, in Chinese translation 七曜. At that time, people created simple handwritten almanacs, where Sunday was marked with the character 密.<ref>{{Cite book |last1=沙畹 |title=摩尼教流行中國攷 |last2=馮承鈞 |publisher=商務印書館 |year=1931}}</ref> The seven-day week had fallen out of favour for a long time, only to be revived when Christianity gained a foothold in China and later made mandatory by the government.
[[File:星房虛昴停印.jpg|thumb|"星房虛昴" denoted  Sunday]]
[[File:會天曆_Calendar.png|thumb|"牛", "女" and "虛" of 28-day cycle in an almanac, falling on Friday, Saturday and Sunday, respectively. (Line read from right to left)]]
In between, a 28-day cycle system was used, borrowing from the [[Twenty-Eight Mansions]] system. Originally, these mansions tracked the moon's position against the stars in the sky, much like the sun and zodiac, and became part of the [[Chinese constellations]]. However, in this context, the 28-day cycle had no connection to astronomy and was used purely for fortune-telling. This information was documented and is still referenced in the ''Tung Shing'', a Chinese almanac. When Westerners introduced the seven-day week system to China, whether for religious, business, or colonial reasons, both the Chinese and the Westerners found the 28-day cycle useful. Sunday, for instance, was written as "星房虛昴," indicating the corresponding four days on the 28-day cycle, as easily found in the almanac.<ref>{{Cite book |last1=允祿 |title=欽定協紀辨方書 |last2=梅瑴成 |year=1739 |language=lzh}}</ref>

Following the calendrical reforms in China during the era of the Republic of China, a period marked by both rejection and integration, the seven-day week system became the most widely used, aligning with the Western world.<ref>{{Cite web |title=Calendrical Reform in China, 1911–Present |url=https://studylib.net/doc/7586811/calendrical-reform-in-china--1911-present |access-date=2025-07-18 |website=studylib.net |language=en}}</ref>
{| class="wikitable"
|+Seven-day week comparison
|Chinese
|日
|月
|火星
|水星
|木星
|金星
|土星
|-
|Literal meaning
|sun
|moon
|fire star
|water star
|wood star
|metal star
|earth star
|-
|English meaning
|Sun
|Moon
|Mars
|Mercury
|Jupiter
|Venus
|Saturn
|-
|七曜, ''the seven shiny''
|日曜日
|月曜日
|火曜日
|水曜日
|木曜日
|金曜日
|土曜日
|-
|literal meaning
|''Sun-day''
|Moon-day
|Mars-day
|Mercury-day
|Jupiter-day
|Venus-day
|Saturn-day
|-
|Sogdian names
|Mīr
|Māq
|Wnqān
|Tīr
|Wrnzt
|Nāqit
|Kēwān
|-
|Chinese phonic translation
|密/蜜
|莫
|雲漢
|咥/嘀
|溫沒司/嗢沒司/鶻勿斯
|那頡/那歇/般頡
|雞緩/枳浣
|-
|Modern English
|Sunday
|Monday
|Tuesday
|Wednesday
|Thursday
|Friday
|Saturday
|-
|Modern Chinese
|星期日
|星期一
|星期二
|星期三
|星期四
|星期五
|星期六
|-
|Hong Kong variant
|禮拜日
|禮拜一
|禮拜二
|禮拜三
|禮拜四
|禮拜五
|禮拜六
|-
| rowspan="4" |28-day cycle, borrowing from Twenty-Eight Mansions
|星
|張
|翼
|軫
|角
|亢
|氐
|-
|房
|心
|尾
|箕
|斗
|牛
|女
|-
|虛
|危
|室
|室
|壁
|奎
|婁
|-
|昴
|畢
|觜
|參
|井
|鬼
|柳
|}

===Month===
{{See also|Month}}
Months are [[Moon]] oriented. ''Month'' ({{lang-zh|labels=no|c=月|p=yuè}}), the time from one [[new moon]] to the next. These [[Lunar month#Synodic month|synodic months]] are about {{frac|29|17|32}} days long. This includes the ''Date'' ({{lang-zh|labels=no|c=日期|p=rìqī}}), when a day occurs in the month. Days are numbered in sequence from 1 to 29 (or 30). And, a ''Calendar month'' ({{lang-zh|labels=no|c=日曆月|p=rìlì yuè}}), is when a month occurs within a year. Some months may be repeated.

Months are defined by the time between [[new moon]]s, which averages approximately {{frac|29|17|32}} days. There is no specified length of any particular Chinese month, so the first month could have 29 days (short month, {{linktext|小月|lang=zh}}) in some years and 30 days (long month, {{linktext|大月|lang=zh}}) in other years.

Since the beginning of the month is determined by when the new moon occurs, other countries using this calendar use their own time standards to calculate it, resulting in deviations. The first new moon in 1968 was at 16:29 [[Coordinated Universal Time|UTC]] on 29 January. Since [[North Vietnam]] used [[UTC+07:00]] to calculate their [[Vietnamese calendar]] and [[South Vietnam]] used [[UTC+08:00]] (Beijing time) to calculate theirs, North Vietnam began the [[Tết]] holiday at 29 January at 23:29 while South Vietnam began it on 30 January at 00:15. The time difference allowed asynchronous attacks in the [[Tet Offensive]].{{sfnp|Aslaksen|2010}}

Because astronomical observation determines month length, dates on the calendar correspond to moon phases. The first day of each month is the new moon. On the seventh or eighth day of each month, the first-quarter moon is visible in the afternoon and early evening. On the 15th or 16th day of each month, the full moon is visible all night. On the 22nd or 23rd day of each month, the last-quarter moon is visible late at night and in the morning.

Different eras used different systems to determine the length of each month. The [[Lunar month#Synodic month|synodic month]] of the Taichu calendar was {{frac|29|43|81}} days long. The 7th-century, Tang-dynasty Wùyín Yuán Calendar was the first to determine month length by synodic month instead of the cycling method. Since then, month lengths have primarily been determined by observation and prediction.

The days of the month are always written with two characters and numbered beginning with 1. Days one to 10 are written with the day's numeral, preceded by the character ''Chū'' ({{linktext|初|lang=zh}}); ''Chūyī'' ({{linktext|初一|lang=zh}}) is the first day of the month, and ''Chūshí'' ({{linktext|初|十|lang=zh}}) the 10th. Days 11 to 20 are written as regular [[Chinese numerals]]; ''Shíwǔ'' ({{linktext|十五|lang=zh}}) is the 15th day of the month, and ''Èrshí'' ({{linktext|二十|lang=zh}}) the 20th. Days 21 to 29 are written with the character ''Niàn'' ({{linktext|廿|lang=zh}}) before the characters one through nine; ''Niànsān'' ({{linktext|廿三|lang=zh}}), for example, is the 23rd day of the month. Day 30 (when applicable) is written as the numeral ''Sānshí'' ({{linktext|三十|lang=zh}}).

===Year===
{{See also|Year}}

A year ({{lang-zh|labels=no|c=年|p=nián}}) is based upon the time of one revolution of Earth around the Sun, rounded to whole days. Traditionally, the year is measured from the first day of spring (lunisolar year) or the winter solstice (solar year).

A 12-month-year using this system has 354 days, which would drift significantly from the [[tropical year]]. To fix this, traditional Chinese years have a 13-month year approximately once every three years. The 13-month version has the same long and short months alternating, but adds a 30-day leap month ({{lang-zh|labels=no|c={{linktext|閏月}}|p=rùnyuè}}). Years with 12 months are called common years, and 13-month years are known as long years.

A solar year is astronomically about {{frac|365|31|128}} days. A lunisolar calendar year is either 353–355 or 383–385 days long. The lunisolar calendar ({{lang-zh|labels=no|c=日曆|p=rìlì}}) year usually begins on the new moon closest to [[Lichun]], the first day of spring.{{sfnp|Aslaksen|2010}} This is typically the second and sometimes third new moon after the winter solstice.

The lunisolar year begins with the first spring month, {{tlit|zh|pinyin|[[Zhengyue|''Zhēngyuè'']]}} ({{lang-zh|labels=no|c={{linktext|正月}}|l=capital month}}), and ends with the last winter month, {{tlit|zh|pinyin|[[Layue|''Làyuè'']]}} ({{lang-zh|labels=no|s={{linktext|腊月}}|t={{linktext|臘月}}|l=sacrificial month}}). All other months are named for their number in the month order. See [[#Chinese New Year|below]] on the timing of the Chinese New Year.

==== Solar year and solar terms ====
{{Main|Solar term}}
The [[Tropical year|solar year]] ({{lang-zh|s=岁|t=歲|p=Suì}}), the time between [[winter solstice]]s, is divided into 24 periods. Each period corresponds to a 15°-portion of the ecliptic. The 24 moments of transition, known as {{lang-zh|labels=no|out=p|p=jié qì|c=節氣}}, [[solar term]]s or solar nodes, mark off the seasons (both Western and Chinese), corresponding to equinoxes, solstices, and other Chinese events. The solar terms are paired{{ndash}}one corresponding to the sun being a multiplel of 30° from a solstice, called "major" terms, or {{tlit|zh|pinyin|Zhōngqì}}, and the other corresponding to the sun being 15° further west (earlier in the year), called "minor" terms. (The word jié qì can also be used to refer just to these.){{sfnp|Aslaksen|2010}} The solar terms {{lang-zh|labels=no|out=p|p=qīng míng|c=清明}} around 5 April and {{lang-zh|labels=no|out=p|p=dōng zhì |c=冬至}} around 22 December are celebrated events in China.{{sfnp|Aslaksen|2010}}

The solar year (''suì'', {{lang-zh|labels=no|t=歲|s=岁}}) begins on the December solstice and proceeds through the 24 solar terms.{{sfnp|Aslaksen|2010}} Since the speed of the Sun's apparent motion in the elliptical is variable, the time between major terms is not fixed. This variation in time between major terms results in different solar year lengths. There are generally 11 or 12 complete lunisolar months, plus two incomplete lunisolar months around the winter solstice, in a solar year. The complete lunisolar months are numbered from 0 to 10, and the lunisolar month split between two solar years is considered the 11th month. If there are 12 complete lunisolar months within a solar year, it is known as a leap year (a year possessing an intercalary month).{{sfnp|Aslaksen|2010}}

Different versions of the traditional calendar might have different average solar year lengths. For example, one solar year of the 1st century BCE Tàichū calendar is {{frac|365|385|1539}} (365.25016) days. A solar year of the 13th-century Shòushí calendar is {{frac|365|97|400}} (365.2425) days, identical to the Gregorian calendar. The additional .00766 day from the Tàichū calendar leads to a one-day shift every 130.5 years.

{| class="wikitable"
|+24 solar terms
!Number
!Pinyin name
!Chinese name
!Translation
!Approximate date
!Corresponding astrological sign
|-
|J1
|{{tlit|zh|pinyin|Lì chūn}}
|{{lang|zh|立春}}
|Beginning of spring
|5 February
|♒️ Aquarius
|-
|Z1
|{{tlit|zh|pinyin|Yǔ shuǐ}}
|{{lang|zh|雨水}}
|Rain water
|19 February
| rowspan="2" |♓️ Pisces
|-
|J2
|{{tlit|zh|pinyin|Jīng zhé}}
|{{lang|zh-hant|驚蟄}}；{{lang|zh-hans|惊蛰}}
|Waking of insects
|6 March
|-
|Z2
|{{tlit|zh|pinyin|Chūn fēn}}
|{{lang|zh|春分}}
|Spring divide
|21 March
| rowspan="2" |♈️ Aries
|-
|J3
|{{tlit|zh|pinyin|Qīng míng}}
|{{lang|zh|清明}}
|[[Qingming Festival|Pure brightness]]
|5 April
|-
|Z3
|{{tlit|zh|pinyin|Gǔ yǔ}}
|{{lang|zh-hant|穀雨}}；{{lang|zh-hans|谷雨}}
|Grain rain
|20 April
| rowspan="2" |♉️ Taurus
|-
|J4
|{{tlit|zh|pinyin|Lì xià}}
|{{lang|zh|立夏}}
|Beginning of summer
|6 May
|-
|Z4
|{{tlit|zh|pinyin|Xiǎo mǎn}}
|{{lang|zh-hant|小滿}}；{{lang|zh-hans|小满}}
|Grain full
|21 May
| rowspan="2" |♊️ Gemini
|-
|J5
|{{tlit|zh|pinyin|Máng zhòng}}
|{{lang|zh-hant|芒種}}；{{lang|zh-hans|芒种}}
|Grain in ear
|6 June
|-
|Z5
|{{tlit|zh|pinyin|Xià zhì}}
|{{lang|zh|夏至}}
|Summer extremity
|22 June
| rowspan="2" |♋️ Cancer
|-
|J6
|{{tlit|zh|pinyin|Xiǎo shǔ}}
|{{lang|zh|小暑}}
|Slight heat
|7 July
|-
|Z6
|{{tlit|zh|pinyin|Dà shǔ}}
|{{lang|zh|大暑}}
|Great heat
|23 July
| rowspan="2" |♌️ Leo
|-
|J7
|{{tlit|zh|pinyin|Lì qiū}}
|{{lang|zh|立秋}}
|Beginning of autumn
|8 August
|-
|Z7
|{{tlit|zh|pinyin|Chǔ shǔ}}
|{{lang|zh-hant|處暑}}；{{lang|zh-hans|处暑}}
|Limit of heat
|23 August
| rowspan="2" |♍️ Virgo
|-
|J8
|{{tlit|zh|pinyin|Bái lù}}
|{{lang|zh|白露}}
|White dew
|8 September
|-
|Z8
|{{tlit|zh|pinyin|Qiū fēn}}
|{{lang|zh|秋分}}
|Autumn divide
|23 September
| rowspan="2" |♎️ Libra
|-
|J9
|{{tlit|zh|pinyin|Hán lù}}
|{{lang|zh|寒露}}
|Cold dew
|8 October
|-
|Z9
|{{tlit|zh|pinyin|Shuāng jiàng}}
|{{lang|zh|霜降}}
|Descent of frost
|24 October
| rowspan="2" |♏️ Scorpio
|-
|J10
|{{tlit|zh|pinyin|Lì dōng}}
|{{lang|zh|立冬}}
|Beginning of winter
|8 November
|-
|Z10
|{{tlit|zh|pinyin|Xiǎo xuě}}
|{{lang|zh|小雪}}
|Slight snow
|22 November
| rowspan="2" |♐️ Sagittarius
|-
|J11
|{{tlit|zh|pinyin|Dà xuě}}
|{{lang|zh|大雪}}
|Great snow
|7 December
|-
|Z11
|{{tlit|zh|pinyin|Dōng zhì}}
|{{lang|zh|冬至}}
|Winter extremity
|22 December
| rowspan="2" |♑️ Capricorn
|-
|J12
|{{tlit|zh|pinyin|Xiǎo hán}}
|{{lang|zh|小寒}}
|Slight cold
|6 January
|-
|Z12
|{{tlit|zh|pinyin|Dà hán}}
|{{lang|zh|大寒}}
|Great cold
|20 January
|♒️ Aquarius
|}

If there are 12 complete lunisolar months within a solar year, the first lunisolar month that does not contain a major term is designated the [[Intercalation (timekeeping)|leap]], or intercalary, month.{{sfnp|Aslaksen|2010}} (Quite rarely there is a year having a month that contains no major term but which is not counted as a leap month because there is another month later which contains two. This will happen in 2033.{{sfnp|Aslaksen|2010}}) Leap months are numbered with {{tlit|zh|pinyin|rùn}} {{linktext|閏|lang=zh}}, the character for "intercalary", plus the name of the month they follow. In 2017, the intercalary month after month six was called {{tlit|zh|pinyin|Rùn Liùyuè}}, or "intercalary sixth month" ({{linktext|閏|六月|lang=zh}}) and written as ''6i'' or ''6+''. The next intercalary month (in 2020, after month four) is called {{tlit|zh|pinyin|Rùn Sìyuè}} ({{linktext|閏|四月|lang=zh}}) and written ''4i'' or ''4+''.

Leap months occur on average once in {{frac|2|5|7}} years, or {{frac|33|4|7}} months (because of the [[Metonic cycle]] of 19 years equaling 235 months), but this varies because the speed of the moon, and of the sun, varies.

===Planets===
The movements of the Sun, Moon, [[Mercury (planet)|Mercury]], [[Venus]], [[Mars]], [[Jupiter]] and [[Saturn]] (sometimes known as the [[Classical planet|seven luminaries]]) are the references for calendar calculations. 
* The distance between Mercury and the sun is less than 30° (the sun's height at ''chénshí'':{{linktext|辰時|lang=zh}}, 8:00 to 10:00&nbsp;am), so Mercury was sometimes called the "chen star" ({{linktext|辰|星|lang=zh}}); it is more commonly known as the "water star" ({{linktext|水星|lang=zh}}).
* Venus appears at dawn and dusk and is known as the "bright star" ({{lang-zh|labels=no|s={{linktext|启明|星}}|t={{linktext|啟明|星}}}}) or "long star" ({{lang-zh|labels=no|c=|s={{linktext|长庚|星}}|t={{linktext|長庚|星}}}}).
* Mars looks like fire and occurs irregularly, and is known as the "fire star" ({{lang-zh|labels=no|c=|s={{linktext|荧惑|星}}|t={{linktext|熒惑|星}}}} or {{linktext|火星|lang=zh}}). Mars is the punisher in Chinese mythology. When Mars is near [[Antares]] ({{linktext|心宿二|lang=zh}}), it is a bad omen and can forecast an emperor's death or a chancellor's removal ({{linktext|荧惑|守|心|lang=zh}}).
* Jupiter's revolution period is 11.86 years, so Jupiter is called the "age star" ({{lang-zh|labels=no|c=|s={{linktext|岁星}}|t={{linktext|歲星}}}}); 30° of Jupiter's revolution is about a year on earth.
* Saturn's revolution period is about 28 years. Known as the "guard star" ({{linktext|鎮星|lang=zh}}), Saturn guards one of the [[Twenty-Eight Mansions|28 Mansions]] every year.

===Stars===
====Big Dipper====
{{Main|Big Dipper}}
The [[Big Dipper]] is the celestial compass, and its handle's direction indicates the season and month.

====3 Enclosures and 28 Mansions====
{{Main|Chinese constellations}}
{{Further|Twenty-Eight Mansions|Lunar station}}

The stars are divided into [[Chinese constellations#Three Enclosures|Three Enclosures]] and [[Twenty-Eight Mansions|28 Mansions]] according to their location in the sky relative to [[Ursa Minor]], at the center. Each mansion is named with a character describing the shape of its principal [[asterism (astronomy)|asterism]]. The Three Enclosures are [[Purple Forbidden enclosure|Purple Forbidden]], ({{linktext|紫微|lang=zh}}), [[Supreme Palace enclosure|Supreme Palace]] ({{linktext|太微|lang=zh}}), and [[Heavenly Market enclosure|Heavenly Market]] ({{linktext|天市|lang=zh}}). The eastern mansions are {{lang|zh|{{linktext|角}}, {{linktext|亢}}, {{linktext|氐}}, {{linktext|房}}, {{linktext|心}}, {{linktext|尾}}, {{linktext|箕}}}}. Southern mansions are {{lang|zh|{{linktext|井}}, {{linktext|鬼}}, {{linktext|柳}}, {{linktext|星}}, {{linktext|張}}, {{linktext|翼}}, {{linktext|軫|}}}}. Western mansions are {{lang|zh|{{linktext|奎}}, {{linktext|婁}}, {{linktext|胃}}, {{linktext|昴}}, {{linktext|畢}}, {{linktext|參}}, {{linktext|觜}}}}. Northern mansions are {{lang|zh|{{linktext|斗}}, {{linktext|牛}}, {{linktext|女}}, {{linktext|虛}}, {{linktext|危}}, {{linktext|室}}, {{linktext|壁}}}}. The moon moves through about one [[lunar mansion]] per day, so the 28 mansions were also used to count days. In the [[Tang dynasty]], Yuan Tiangang ({{lang|zh|袁天罡}}) matched the 28 mansions, seven luminaries and yearly animal signs to yield combinations such as "horn-wood-flood dragon" ({{linktext|角|木|蛟|lang=zh}}).

===== List of lunar mansions =====

The names and determinative stars of the mansions are:<ref>{{cite web | url=http://idp.bl.uk/education/astronomy/sky.html | title=The Chinese Sky | publisher=[[International Dunhuang Project]] | accessdate=2011-06-25 | url-status=dead | archiveurl=https://web.archive.org/web/20151104154237/http://idp.bl.uk/education/astronomy/sky.html | archivedate=2015-11-04 }}</ref><ref>{{cite book | last=Sun | first=Xiaochun | editor=Helaine Selin | editor-link=Helaine Selin | title=Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures  | url=https://books.google.com/books?id=raKRY3KQspsC&pg=PA517 | year=1997 | pages=517 | publisher=Kluwer Academic Publishers | isbn=0-7923-4066-3  | accessdate=2011-06-25}}</ref>
{| class="wikitable"
|-
!rowspan="2" align="center"|[[Four Symbols (Chinese constellation)|Four Symbols]]<br/>({{lang|zh|四象}}) !! colspan="4" align="center" | Mansion (宿)
|-
!Number
!Name 
([[Pinyin]])
!Translation
!Determinative star
|-
|rowspan="7" |'''[[Azure Dragon|Azure Dragon<br/>of the East]]<br/>({{lang-zh|labels=no|c=東方青龍|p=Dōngfāng Qīnglóng}})<br/>Spring'''[[File:AZURE DRAGON.png|center|frameless|103x103px]]
| 1 || {{lang-zh|labels=no|c=角|p=Jiǎo}} ||[[Horn (Chinese constellation)|Horn]] || [[Spica|α Vir]]
|-
| 2 || {{lang-zh|labels=no|c=亢 |p=Kàng}} ||[[Neck (Chinese constellation)|Neck]] || [[Kappa Virginis|κ Vir]]
|-
| 3 || {{lang-zh|labels=no|c=氐 |p=Dī}} ||[[Root (Chinese constellation)|Root]] || [[Zubenelgenubi|α Lib]]
|-
| 4 || {{lang-zh|labels=no|c=房 |p=Fáng}} ||[[Room (Chinese constellation)|Room]] || [[Pi Scorpii|π Sco]]
|-
| 5 || {{lang-zh|labels=no|c=心 |p=Xīn}} ||[[Heart (Chinese constellation)|Heart]] || [[Alpha Scorpii|α Sco]]
|-
| 6 || {{lang-zh|labels=no|c=尾 |p=Wěi}} ||[[Tail (Chinese constellation)|Tail]] || [[Mu1 Scorpii|μ¹ Sco]]
|-
| 7 || {{lang-zh|labels=no|c=箕 |p=Jī}} ||[[Winnowing Basket (Chinese constellation)|Winnowing Basket]] || [[Gamma Sagittarii|γ Sgr]]
|-
|rowspan="7" |'''[[Black Tortoise|Black Tortoise<br/>of the North]]<br/>({{lang-zh|labels=no|c=北方玄武|p=Běifāng Xuánwǔ}})<br/>Winter'''[[File:BLACK TORTOISE.png|center|frameless|101x101px]]<br />
| 8 || {{lang-zh|labels=no|c=斗 |p=Dǒu}} || (Southern) [[Dipper (Chinese constellation)|Dipper]] || [[Phi Sagittarii|φ Sgr]]
|-
| 9 || {{lang-zh|labels=no|c=牛 |p=Niú}} ||[[Ox (Chinese constellation)|Ox]] || [[Dabih|β Cap]]
|-
| 10 || {{lang-zh|labels=no|c=女 |p=Nǚ}} ||[[Girl (Chinese constellation)|Girl]] || [[Albali|ε Aqr]]
|-
| 11 || {{lang-zh|labels=no|c=虛 |p=Xū}} ||[[Emptiness (Chinese constellation)|Emptiness]] || [[Sadalsuud|β Aqr]]
|-
| 12 || {{lang-zh|labels=no|c=危 |p=Wēi}} ||[[Rooftop (Chinese constellation)|Rooftop]] || [[Sadalmelik|α Aqr]]
|-
| 13 || {{lang-zh|labels=no|c=室 |p=Shì}} ||[[Encampment (Chinese constellation)|Encampment]] || [[Alpha Pegasi|α Peg]]
|-
| 14 || {{lang-zh|labels=no|c=壁 |p=Bì}} ||[[Wall (Chinese constellation)|Wall]] || [[Gamma Pegasi|γ Peg]]
|-
|rowspan="7" |'''[[White Tiger (Chinese astronomy)|White Tiger<br/>of the West]]<br/>({{lang-zh|labels=no|c=西方白虎|p=Xīfāng Báihǔ}})<br/>Fall'''[[File:WHITE TIGER OF THE WEST (CHINESE MYTHOLOGY).png|center|frameless|103x103px]]<br />
| 15 || {{lang-zh|labels=no|c=奎 |p=Kuí}} ||[[Legs (Chinese constellation)|Legs]] || [[Eta Andromedae|η And]]
|-
| 16 || {{lang-zh|labels=no|c=婁 |p=Lóu}} ||[[Bond (Chinese constellation)|Bond]] || [[Sheratan|β Ari]]
|-
| 17 || {{lang-zh|labels=no|c=胃 |p=Wèi}} ||[[Stomach (Chinese constellation)|Stomach]] || [[35 Arietis|35 Ari]]
|-
| 18 || {{lang-zh|labels=no|c=昴 |p=Mǎo}} ||[[Hairy Head (Chinese constellation)|Hairy Head]] || [[Electra (star)|17 Tau]]
|-
| 19 || {{lang-zh|labels=no|c=畢|p=Bì}} ||[[Net (Chinese constellation)|Net]] || [[Epsilon Tauri|ε Tau]]
|-
| 20 || {{lang-zh|labels=no|c=觜 |p=Zī}} ||[[Turtle Beak (Chinese constellation)|Turtle Beak]] || [[Meissa|λ Ori]]
|-
| 21 || {{lang-zh|labels=no|c=参 |p=Shēn}} ||[[Three Stars (Chinese constellation)|Three Stars]] || [[Alnitak|ζ Ori]]
|-
|rowspan="7" |'''[[Vermilion Bird|Vermilion Bird<br/>of the South]]<br/>({{lang-zh|labels=no|c=南方朱雀 |p=Nánfāng Zhūquè}})<br/>Summer'''[[File:VERMILION BIRD.png|center|frameless|102x102px]]<br />
| 22 || {{lang-zh|labels=no|c=井 |p=Jǐng}} ||[[Well (Chinese constellation)|Well]] || [[Tejat Posterior|μ Gem]]
|-
| 23 || {{lang-zh|labels=no|c=鬼 |p=Guǐ}} ||[[Ghost (Chinese constellation)|Ghost]] || [[Theta Cancri|θ Cnc]]
|-
| 24 || {{lang-zh|labels=no|c=柳 |p=Liǔ}} ||[[Willow (Chinese constellation)|Willow]] || [[Delta Hydrae|δ Hya]]
|-
| 25 || {{lang-zh|labels=no|c=星 |p=Xīng}} ||[[Star (Chinese constellation)|Star]] || [[Alphard|α Hya]]
|-
| 26 || {{lang-zh|labels=no|c=張 |p=Zhāng}} ||[[Extended Net (Chinese constellation)|Extended Net]] || [[Upsilon1 Hydrae|υ¹ Hya]]
|-
| 27 || {{lang-zh|labels=no|c=翼 |p=Yì}} ||[[Wings (Chinese constellation)|Wings]] || [[Alkes|α Crt]]
|-
| 28 || {{lang-zh|labels=no|c=軫 |p=Zhěn}} ||[[Chariot (Chinese constellation)|Chariot]] || [[Gienah Corvi|γ Crv]]
|}

== Sexagenary system==
Several coding systems are used to avoid ambiguity. The [[Heavenly Stems]] is a [[decimal]] system. The [[Earthly Branches]], a [[duodecimal]] system, mark dual hours ({{lang-zh|labels=no|p=shí|t={{linktext|時}}|s={{linktext|时}}}} or {{lang-zh|labels=no|p=shíchen|t={{linktext|時辰}}|s={{linktext|时辰}}}}) and climatic terms. The 12 characters progress from the first day with the same branch as the month (first {{tlit|zh|pinyin|Yín}} day ({{linktext|寅|日|lang=zh}}) of {{tlit|zh|pinyin|Zhēngyuè}}; first {{tlit|zh|pinyin|Mǎo}} day ({{linktext|卯|日|lang=zh}}) of {{tlit|zh|pinyin|Èryuè}}), and count the days of the month.

{{Main|Sexagenary cycle}}
Years, months, days of the month and hours could traditionally numbered by the terminology of the Chinese sexagenary cycle.

The [[Sexagenary cycle|stem-branches]] is a [[sexagesimal]] system. The Heavenly Stems and Earthly Branches make up [[Sexagenary cycle|60 stem-branches]]. The stem branches mark days and years. The five [[Wuxing (Chinese philosophy)|Wu Xing]] elements are assigned to each stem, branch, or stem branch.

{| class="wikitable" border="1"
! rowspan="2" | Heavenly<br />Stem !! colspan="2" | Meaning
|-
! Original meaning !! Modern
|-
|{{lang|zh|甲}}|| [[turtle shell]] || ''first (book I, person A etc.)'', ''methyl group'', helmet, armor, words related to beetles, crustaceans, fingernails, toenails
|-
|{{lang|zh|乙}}|| [[fishguts]] || ''second (book II, person B etc.)'', ''ethyl group'', twist
|-
|{{lang|zh|丙}}|| [[caudal fin|fishtail]]{{efn|Wenlin Dictionary: Picture of a fish tail.{{Full citation needed|date=February 2025}}}}|| ''third'', bright, fire, fishtail (rare)
|-
|{{lang|zh|丁}}|| [[Nail (fastener)|nail]] || ''fourth'', male adult, robust, T-shaped, to strike, a surname
|-
|{{lang|zh|戊}}|| [[halberd]] || (not used)
|-
|{{lang|zh|己}}|| threads on a loom{{efn|Wenlin Dictionary: {{lang|zh|己}} may have depicted [[Thread (yarn)|thread]] on a [[loom]]; an ancient meaning was 'unravel threads', which was later written {{lang|zh|紀}} jì. {{lang|zh|己}} was borrowed both for the word jǐ 'self', and for the name of the sixth Heavenly Stem ({{lang|zh|天干}}).{{Full citation needed|date=February 2025}}}} || self
|-
|{{lang|zh|庚}}|| evening star || age (of person)
|-
|{{lang|zh|辛}}|| to offend superiors<ref>Wenlin Dictionary: "The seal has {{lang|zh|𢆉}} 'knock against, offend' below, and {{lang|zh|亠}} above; the scholastic commentators say: to offend ({{lang|zh|亠}} = ) {{lang|zh|上}} the superiors"{{Full citation needed|date=February 2025}}</ref> || bitter, piquant, toilsome
|-
|{{lang|zh|壬}}|| burden{{efn|Wenlin Dictionary: {{lang|zh|壬}} rén depicts "a 丨 carrying pole supported 一 in the middle part and having one object attached at each end, as always done in China" —Karlgren (1923). (See {{lang|zh|扁担}} biǎndan). Now the character {{lang|zh|任}} rèn has the meaning of carrying a burden, and the original character {{lang|zh|壬}} is used only for the ninth of the ten heavenly stems ({{lang|zh|天干}}).{{Full citation needed|date=February 2025}}}} || to shoulder, to trust with office
|-
|{{lang|zh|癸}}|| grass for libation{{efn|Wenlin Dictionary: {{lang|zh|癶}} "stretch out the legs" + {{lang|zh|天}}; The nicely disposed grass, on which the Ancients poured the libations offered to the Manes{{Full citation needed|date=February 2025}}}}|| (not used)
|}

{|class="wikitable"
!rowspan=2|&nbsp;
!rowspan=2|Earthly<br />Branch
!colspan=3|Chinese
!rowspan=2|Direction
!rowspan=2|Season
!rowspan=2|Lunisolar Month
!rowspan=2|Double Hour
|-
!Mandarin<br />[[Zhuyin]]!!Mandarin<br />[[Pinyin]]!!Character
|-tr align="center"
||1||{{linktext|子|lang=zh}}||{{lang|zh-Bopo|ㄗˇ}}||{{tlit|zh|pinyin|zǐ}}||{{lang|zh|鼠}}<br />[[Rat (zodiac)|Rat]]||0° (north)||rowspan="2"|winter||Month 11||23 to 1 (midnight)
|-tr align="center"
||2||{{linktext|丑|lang=zh}}||{{lang|zh-Bopo|ㄔㄡˇ}}||{{tlit|zh|pinyin|chǒu}}||{{lang|zh|牛}} <br /> [[Ox (zodiac)|Cow]]||30°||Month 12||1 to 3
|-tr align="center"
||3||{{linktext|寅|lang=zh}}||{{lang|zh-Bopo|ㄧㄣˊ}}||{{tlit|zh|pinyin|yín}}||{{lang|zh|虎}}<br />[[Tiger (zodiac)|Tiger]]||60°||td rowspan="3"|spring||Month 1||3 to 5
|-tr align="center"
||4||{{linktext|卯|lang=zh}}||{{lang|zh-Bopo|ㄇㄠˇ}}||{{tlit|zh|pinyin|mǎo}}||{{lang|zh|兔}}<br />[[Rabbit (zodiac)|Rabbit]]||90° (east)||Month 2||5 to 7
|-tr align="center"
||5||{{linktext|辰|lang=zh}}||{{lang|zh-Bopo|ㄔㄣˊ}}||{{tlit|zh|pinyin|chén}}||{{lang|zh|龍}}<br />[[Dragon (zodiac)|Dragon]]||120°||Month 3||7 to 9
|-tr align="center"
||6||{{linktext|巳|lang=zh}}||{{lang|zh-Bopo|ㄙˋ}}||{{tlit|zh|pinyin|sì}}||{{lang|zh|蛇}}<br />[[Snake (zodiac)|Snake]]||150°||td rowspan="3"|summer||Month 4||9 to 11
|-tr align="center"
||7||{{linktext|午|lang=zh}}||{{lang|zh-Bopo|ㄨˇ}}||{{tlit|zh|pinyin|wǔ}}||{{lang|zh|馬}}<br />[[Horse (zodiac)|Horse]]||180° (south)||Month 5||11 to 13 (noon)
|-tr align="center"
||8||{{linktext|未|lang=zh}}||{{lang|zh-Bopo|ㄨㄟˋ}}||{{tlit|zh|pinyin|wèi}}||{{lang|zh|羊}}<br />[[Goat (zodiac)|Sheep]]||210°||Month 6||13 to 15
|-tr align="center"
||9||{{linktext|申|lang=zh}}||{{lang|zh-Bopo|ㄕㄣ}}||{{tlit|zh|pinyin|shēn}}||{{lang|zh|猴}}<br />[[Monkey (zodiac)|Monkey]]||240°||td rowspan="3"|autumn||Month 7||315 to 17
|-tr align="center"
||10||{{linktext|酉|lang=zh}}||{{lang|zh-Bopo|ㄧㄡˇ}}||{{tlit|zh|pinyin|yǒu}}||{{lang|zh|雞}} <br /> [[Rooster (zodiac)|Chicken]]||270° (west)||Month 8||17 to 19
|-tr align="center"
||11||{{linktext|戌|lang=zh}}||{{lang|zh-Bopo|ㄒㄩ}}||{{tlit|zh|pinyin|xū}}||{{lang|zh|犬}}<br />[[Dog (zodiac)|Dog]]||300°||Month 9||19 to 21
|-tr align="center"
||12||{{linktext|亥|lang=zh}}||{{lang|zh-Bopo|ㄏㄞˋ}}||{{tlit|zh|pinyin|hài}}||{{lang|zh|猪}}<br />[[Wild boar]]||330°||winter||Month 10||21 to 23
|}

For example, the year from 12 February 2021 to 31 January 2022 was a {{tlit|zh|pinyin|Xīnchǒu}} year ({{linktext|辛丑|年|lang=zh}}) of 12 months or 354 days. The 60 stem-branches have been used to mark the year since the [[Shang dynasty]] (1600 BCE – 1046 BCE). Astrologers knew that the orbital period of [[Jupiter]] is about 12×361 = 4332 days, which they divided into 12 years ({{lang-zh|labels=no|s=岁|t=歲|p=suì}}) of 361 days each. The stem-branches system solved the era system's problem of unequal reign lengths.
[[File:ROC Gazette by Hubei Military Government 19111015.jpg|thumb|Hubei military government founded ROC [[Gazetteer|Gazette]] ({{lang|zh|中華民國公報}}), dated YE 4609-10-15 ({{lang|zh|黃帝紀元4609年10月15日}}, yyyy-mm-dd)]]

{{See also|Month|Lunisolar month}}

Current naming conventions use numbers as the month names, although each month is also associated with one of the twelve [[Earthly Branches]]. Correspondences with Gregorian dates are approximate and should be used with caution. Many years have intercalary months.

Historically, Chinese had days of the month numbered with the 60 stem-branches: {{Blockquote| text={{lang|zh|天聖元年…{{linktext|二月}}…{{linktext|丁|巳}}，奉安太祖、太宗御容于南京鴻慶宮}}. <br />{{tlit|zh|pinyin|[[Tiansheng Era (Song)|''Tiānshèng'']]}} 1st year…{{tlit|zh|pinyin|Èryuè}}…{{tlit|zh|pinyin|Dīngsì}}, the emperor's funeral was at his temple, and the imperial portrait was installed in Nanjing's ''Hongqing Palace''. |title=[[History of Song Dynasty]]|sign=|source={{cite wikisource|title=宋史|trans-title=[[History of Song Dynasty]]|chapter=卷009|trans-chapter=Volume 9|wslanguage=zh}}}}

Fortune-tellers identify the [[heavenly stem]] and [[earthly branch]] corresponding to a particular day in the month, and those corresponding to its month, and those to its year, to determine the [[Four Pillars of Destiny]] associated with it, for which the [[Tung Shing]], also referred to as the [[Chinese Almanac]] of the year, or the [[Huangli]], and containing the essential information concerning [[Chinese astrology]], is the most convenient publication to consult. Days rotate through a [[sexagenary cycle]] marked by coordination between [[heavenly stem]]s and [[earthly branch]]es, hence the referral to the [[Four Pillars of Destiny]] as, "Bazi", or "[[Birth Time Eight Characters]]", with each pillar consisting of a character for its corresponding heavenly stem, and another for its earthly branch. Since [[Huangli]] days are [[sexagenary cycle|sexagenaric]], their order is quite independent of their numeric order in each month, and of their numeric order within a week (referred to as [[True Animals]] in relation to the [[Chinese zodiac]]). Therefore, it does require painstaking calculation for one to arrive at the [[Four Pillars of Destiny]] of a particular given date, which rarely outpaces the convenience of simply consulting the [[Huangli]] by looking up its [[Gregorian calendar|Gregorian]] date.

The [[Tang dynasty]] used the Earthly Branches to mark the months from December 761 to May 762.<ref name="new book of tang">{{cite wikisource|title=新唐書|trans-title=[[New Book of Tang]]|chapter=卷006|trans-chapter=Volume 6|wslanguage=zh|quote={{lang|zh|上元…。二年……，九月壬寅，大赦，去「乾元大圣光天文武孝感」号，去「上元」号，称元年，以十一月为岁首，月以斗所建辰为名。…。<br />元年建子月癸巳[2]，…。己亥[9]，…。丙午[16]，…。己酉[29]，…。庚戌[30]，…。[初一壬午大雪，十七冬至]<br/>建丑月辛亥[1]，…。己未[9]，…。乙亥[25]，…。[初一辛亥，初三小寒，十八大寒]<br/>宝应元年建寅月甲申[4]，…。乙酉[5]，…。丙戌[3]，…。甲辰[24]，…。戊申[28]，…。[初一辛巳，初三立春，十八雨水]<br/>建卯月辛亥[1]，…。壬子[2]，…。癸丑[3]，…。乙丑[15]，…。戊辰[18]，…。庚午[20]，…。壬申[22]，…。[初一辛亥，初四惊蛰，十九春分]<br/>建辰月壬午[3]，…。甲午[5]，…。戊申[19]，…。[初一庚辰，初五清明，二十谷雨]<br/>建巳月庚戌[1]，…。壬子[3]，…。甲寅[5]，…。乙丑[16]，…。大赦，改元年为宝应元年，复以正月为岁首，建巳月为四月。丙寅，…。[初一庚戌，初五甲寅立夏]。}}}}</ref> Over this period, the year began with the winter solstice.

{{main|Traditional Chinese timekeeping}}
[[File:Chinese time.png|thumb|alt=See caption|Explanatory chart for traditional Chinese time]]
China has used the Western hour-minute-second system to divide the day since the [[Qing dynasty]].<ref name="units of time">{{cite journal |last1=Sôma |first1=Mitsuru |last2=Kawabata |first2=Kin-aki |last3=Tanikawa |first3=Kiyotaka |title=Units of Time in Ancient China and Japan |journal=Publications of the Astronomical Society of Japan |date=25 October 2004 |volume=56 |issue=5 |pages=887–904 |doi=10.1093/pasj/56.5.887 }}</ref> Several systems were in use historically; systems using multiples of twelve and ten were popular, since they could be easily counted and aligned with the Heavenly Stems and Earthly Branches.

== Age reckoning ==
{{Main|East Asian age reckoning}}
In modern China, a person's official age is based on the Gregorian calendar. For traditional use, age is based on the Chinese ''Sui'' calendar. A child is considered one year old at birth. After each Chinese New Year, one year is added to their traditional age. Their age therefore is the number of Chinese calendar years in which they have lived. Due to the potential for confusion, the age of infants is often given in months instead of years.

After the Gregorian calendar was introduced in China, the Chinese traditional-age was referred to as the "nominal age" ({{lang-zh|labels=no |t=虛歲 |s=虚岁|p=xūsuì|l=incomplete age}}) and the Gregorian age was known as the "real age" ({{lang-zh|labels=no |t=實歲 |s=实岁 |p=shísùi |l=whole age}}). In Hong Kong, they are named as ''hui ling'' 虛齡 and ''sut ling'' 實齡 respectively.

==Holidays==
{{main|List of observances set by the Chinese calendar}}
{{See also|List of festivals in China}}

Various traditional and religious holidays shared by communities throughout the world use the Chinese (Lunisolar) calendar:

=== Chinese New Year ===
{{Main|Chinese New Year}}
The date of the Chinese New Year accords with the patterns of the lunisolar calendar and hence is variable from year to year.

The invariant between years is that the winter solstice, [[Dongzhi (solar term)|Dongzhi]] is required to be in the eleventh month of the year{{sfnp|Reingold|Dershowitz|2018 |pages=313}} This means that Chinese New Year will be on the second new moon after the previous winter solstice, unless there is a leap month 11 or 12 in the previous year.{{sfnp|Aslaksen|2010|pages=31,32}}{{sfnp|Reingold|Dershowitz|2018 |pages=313–316}}

This rule is accurate, however there are two other mostly (but not completely) accurate rules that are commonly stated:{{sfnp|Aslaksen|2010|pages=31,32}}

* The new year is on the new moon closest to [[Lichun]] (typically 4 February).
* The new year is on the first new moon after [[Dahan (solar term)|Dahan]] (typically 20 January)

It has been found that Chinese New Year moves back by either 10, 11, or 12 days in most years. If it falls on or before 31 January, then it moves forward in the next year by either 18, 19, or 20 days.{{sfnp|Aslaksen|2010}}

===Holidays with the same day and same month===
The [[Chinese New Year]] (known as the Spring Festival/{{lang|zh|春節}} in China) is on the first day of the first month and was traditionally called the Yuan Dan ({{lang|zh|元旦}}) or Zheng Ri ({{lang|zh|正日}}). In Vietnam it is known as Tết Nguyên Đán ({{lang|vi|節元旦}}). Traditionally it was the most important holiday of the year. It is an official holiday in China including Hong Kong, Macau, and Taiwan regions,and, Vietnam, Korea, the Philippines, [[Malaysia]], [[Singapore]], Indonesia, and [[Mauritius]]. It is also a public holiday in Thailand's [[Narathiwat]], [[Pattani Province|Pattani]], [[Yala Province|Yala]] and [[Satun]] provinces, and is an official public school holiday in New York City.

The [[Double Third Festival]] is on the third day of the third month.
  
The [[Dragon Boat Festival]], or the [[Duanwu Festival]] ({{lang|zh|端午節}}), is on the fifth day of the fifth month and is an official holiday in China including Hong Kong, Macau, and Taiwan regions.

The [[Qixi Festival]] ({{lang|zh|七夕節}}) is celebrated in the evening of the seventh day of the seventh month.

The [[Double Ninth Festival]] ({{lang|zh|重陽節}}) is celebrated on the ninth day of the ninth month.

===Full moon holidays (holidays on the fifteenth day)===
The [[Lantern Festival]] is celebrated on the fifteenth day of the first month and was traditionally called the Yuan Xiao ({{lang|zh|元宵}}) or Shang Yuan Festival ({{lang|zh|上元節}}).

The [[Zhong Yuan Festival]] is celebrated on the fifteenth day of the seventh month.

The [[Mid-Autumn Festival]] is celebrated on the fifteenth day of the eighth month.

The Xia Yuan Festival is celebrated on the fifteenth day of the tenth month.

===Celebrations of the twelfth month===
The [[Laba Festival]] is on the eighth day of the twelfth month. It is the enlightenment day of Sakyamuni Buddha and in Vietnam is known as {{lang|vi|Lễ Vía Phật Thích Ca thành đạo}}.

The [[Kitchen God Festival]] is celebrated on the twenty-third day of the twelfth month in northern regions of China and on the twenty-fourth day of the twelfth month in southern regions of China.

[[Chinese New Year's Eve]] is also known as the Chuxi Festival and is celebrated on the evening of the last day of the traditional Chinese calendar. It is celebrated wherever the traditional Chinese calendar is observed.

===Celebrations of solar-term holidays===
The [[Qingming Festival]] ({{lang|zh|[[清明]]节}}) is celebrated on the fifteenth day after the Spring Equinox.

The [[Dongzhi Festival]] ({{lang|zh|[[冬至]]}}) or the Winter Solstice is celebrated.

===Religious holidays based on the Chinese calendar===
East Asian [[Mahayana]], [[Taoism|Daoist]], and some [[Caodaism|Cao Dai]] holidays and/or vegetarian observances are based on the traditional Chinese calendar.<ref>{{cite web|url=https://www.fivepeaks.org/english/calendar/guanyin%20vegetarian.htm|title=2020 Buddhist Calendar|access-date=2020-02-04|archive-date=5 February 2020|archive-url=https://web.archive.org/web/20200205005400/https://www.fivepeaks.org/english/calendar/guanyin%20vegetarian.htm|url-status=live}}</ref><ref>{{cite web|url=https://www.fivepeaks.org/english/calendar/vegetarian.htm|title=Mahayana Buddhist Vegetarian Observances|access-date=2020-02-04|archive-date=5 February 2020|archive-url=https://web.archive.org/web/20200205005333/https://www.fivepeaks.org/english/calendar/vegetarian.htm|url-status=live}}</ref><ref>{{cite web|url=https://kknews.cc/culture/gv2zvl.html|script-title=zh:道教節日有哪些?|language=zh-Hant|trans-title=What are Some of the Holidays of Daoism?|access-date=2020-02-04|archive-date=14 August 2021|archive-url=https://web.archive.org/web/20210814144509/https://kknews.cc/culture/gv2zvl.html|url-status=dead}}</ref>

===Celebrations in Japan===
Many of the above holidays of the traditional Chinese calendar are also celebrated in Japan, but since the [[Meiji era]] on the similarly numbered dates of the Gregorian calendar.

===Double celebrations due to intercalary months===
In the case when there is a corresponding [[intercalation (timekeeping)|intercalary month]], the holidays may be celebrated twice. For example, in the hypothetical situation in which there is an additional intercalary seventh month, the Zhong Yuan Festival will be celebrated in the seventh month followed by another celebration in the intercalary seventh month. The next such occasion will be 2033, the first such since the calendar reform of 1645.{{sfnp|Aslaksen|2010}}

==Similar calendars==
Like [[Chinese characters]], variants of the Chinese calendar have been used in different parts of the [[Sinosphere]] throughout history: this includes Vietnam, Korea, Singapore, Japan and Ryukyu, Mongolia, and elsewhere.

=== Outlying areas of China===
Calendars of ethnic groups in mountains and plateaus of southwestern China and grasslands of northern China are based on their [[phenology]] and algorithms of traditional calendars of different periods, particularly the Tang and pre-Qin dynasties.<ref>{{Cite book |last=朱 |first=文鑫 |url=https://taiwanebook.ncl.edu.tw/zh-tw/book/NTUT-9910016635/reader |script-title=zh:曆法通志 |publisher=商務印書館 |year=1934 |edition=1st |location=Shanghai |language=Chinese |access-date=2 May 2023 |archive-date=2 May 2023 |archive-url=https://web.archive.org/web/20230502052544/https://taiwanebook.ncl.edu.tw/zh-tw/book/NTUT-9910016635/reader |url-status=live }}</ref>

===Non-Chinese areas===
[[Korea]], [[Vietnam]], and the [[Ryukyu Islands]] adopted the Chinese calendar. In the respective regions, the Chinese calendar has been adapted into the [[Korean calendar|Korean]], [[Vietnamese calendar|Vietnamese]], and [[Ryukyuan religion#Religious calendar|Ryukyuan calendars]], with the main difference from the Chinese calendar being the use of different [[Meridian (geography)|meridians]] due to geography, leading to some astronomical events — and calendar events based on them — falling on different dates. The traditional [[Japanese calendar]] was also derived from the Chinese calendar (based on a Japanese meridian), but Japan abolished its official use in 1873 after [[Meiji Restoration]] reforms. Calendars in [[Mongolian calendar|Mongolia]]<ref>{{Cite journal |last=Kennedy |first=E. S. |date=1964 |title=The Chinese-Uighur Calendar as Described in the Islamic Sources |jstor=228314 |journal=Isis |volume=55 |issue=4 |pages=435–443 |doi=10.1086/349900 |s2cid=144085088 }}</ref> and [[Tibetan calendar|Tibet]]{{citation needed|date=May 2023}} have absorbed elements of the traditional Chinese calendar but are not direct descendants of it.

== See also ==
{{Portal|China|History}}
* [[Chinese calendar correspondence table]]
* [[Guo Shoujing]], an astronomer tasked with calendar reform during the 13th century
* [[List of festivals in Asia]]
* [[Metonic cycle]] of 19 years, used to reckon leap years with intercalary months in the [[Hebrew calendar|Hebrew]] and [[Babylonian calendar]]s

== Notes ==
{{notelist|30em}}

== References ==
{{Reflist|30em}}

===Sources===
{{refbegin|indent=yes}}
* {{cite web |first=Helmer |last=Aslaksen |title=The Mathematics of the Chinese Calendar |url=https://www.math.nus.edu.sg/~mathelmr/calendar/cal.pdf |date=17 July 2010 |url-status=dead |archive-url=https://web.archive.org/web/20160821170722/https://www.math.nus.edu.sg/~mathelmr/calendar/cal.pdf |archive-date=21 August 2016}}
* {{cite journal |last1=Cohen |first1=Alvin P. |title=Brief Note: The Origin of the Yellow Emperor Era Chronology |journal=Asia Major |date=2012 |volume=25 |issue=2 |pages=1–13 |jstor=43486143 }}
* {{Cite book |last1=Reingold |first1=Edward M |title=Calendrical Calculations |last2=Dershowitz |first2=Nachum |publisher=Cambridge University press |year=2018 |isbn=978-1-107-05762-3 |edition=Ultimate |language=English}}

{{refend}}

== Further reading ==

* {{cite journal |last1=Kai-Lung |first1=Ho |title=The Political Power and the Mongolian Translation of the Chinese Calendar During the Yuan Dynasty |journal=Central Asiatic Journal |date=2006 |volume=50 |issue=1 |pages=57–69 |jstor=41928409 }}

== External links ==
; Calendars
* [http://www.chinesetools.eu/tools/chinesecalendar Chinese months]
* [http://www.hko.gov.hk/en/gts/time/conversion.htm Gregorian-Lunar calendar years] (1901–2100)
* [https://web.archive.org/web/20131004223339/http://china-calendar.com/en_calendar/ Chinese calendar and holidays]
* [http://www.yourchineseastrology.com/calendar/ Chinese calendar with Auspicious Events]
* [http://www.chinesecalendaronline.com Chinese Calendar Online]

; Calendar conversion
* [http://sinocal.sinica.edu.tw 2000-year Chinese-Western calendar converter] From 1 CE to 2100 CE. Useful for historical studies. To use, put the western year 年 month 月day 日in the bottom row and click on 執行.
* [http://lunarcalendar.bitsoftidbits.com/ Western-Chinese calendar converter]

; Rules
* [https://web.archive.org/web/20090712043248/http://www.math.nus.edu.sg/aslaksen/calendar/chinese.html Mathematics of the Chinese Calendar]
* [http://www.hermetic.ch/cal_stud/chinese_cal.htm The Structure of the Chinese Calendar]

{{Clear}}
{{Calendars}}
{{Chinese New Year}}
{{S&T in China}}
{{East Asian topics}}

{{Authority control}}

[[Category:Chinese calendars| ]]
[[Category:Chinese culture|Calendar]]
[[Category:Horology]]
[[Category:Lunisolar calendars]]
[[Category:Specific calendars]]