View source for Ton

{{short description|Unit of mass or volume with different values}}
{{about|the units of measurement||Ton (disambiguation)}}
{{redirect-distinguish|A ton|Aton (disambiguation){{!}}Aton}}
{{Infobox unit
| name         = Ton
| image        = One-ton weight.svg
| caption      = 
| standard     = {{ubl|[[imperial units|British imperial]]|[[US customary units|US customary]]|[[International System of Units#Non-SI units accepted for use with SI|metric]]}}
| quantity     = [[Mass]]
| symbol       = 
| extralabel   = 
| extradata    = 
| units1       = kilograms
| inunits1     = {{cvt|2240|lb|sigfig=8|disp=out}} (ton, long ton)
| units2       = &nbsp;
| inunits2     = {{cvt|2000|lb|sigfig=7|disp=out}} (ton, short ton)
| units3       = &nbsp;
| inunits3     = {{cvt|1|t|kg|sigfig=4|disp=out}} (tonne, metric ton)
| units4       = pounds
| inunits4     = {{cvt|2240|lb|lb|sigfig=4|disp=out}} (ton, long ton)
| units5       = &nbsp;
| inunits5     = {{cvt|2000|lb|lb|sigfig=4|disp=out}} (ton, short ton)
| units6       = &nbsp;
| inunits6     = {{cvt|1|t|lb|sigfig=6|disp=out}} (tonne, metric ton)
| units_imp1   = 
| inunits_imp1 = 
| units_imp2   = 
| inunits_imp2 = 
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| units_imp6   = 
| inunits_imp6 = 
| units_us1    = 
| inunits_us1  =
| units_us2    =
| inunits_us2  =
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| units_us6    = 
| inunits_us6  = 
}}

'''Ton''' is any of several [[unit of measurement|units of measure]] of mass, volume or [[Ton-force|force]]. It has a long history and has acquired several meanings and uses.

As a [[unit of mass]], ''ton'' can mean:
* the ''[[long ton]]'', which is {{convert|2,240|lb|kg|sigfig=5|abbr=off|lk=on}}
* the ''[[tonne]]'', also called the ''metric ton'', which is {{convert|1000|kg|lb|sigfig=5|abbr=off|disp=x| (about }}) or 1 [[megagram]].
* the ''[[short ton]]'', which is {{convert|2,000|lb|kg|sigfig=4|abbr=off|lk=off}}

Its original use as a [[unit of volume]] has continued in the capacity of cargo ships and in units such as the ''[[freight ton]]'' and a number of other units, ranging from {{convert|35|to|100|cuft|m3|lk=on}} in size. 

Because the ton (of any system of measuring weight) is usually the heaviest unit named in [[colloquialism|colloquial]] speech, its name also has figurative uses, singular and plural, informally meaning a large amount or quantity, or to a great degree, as in "There's a ton of bees in this hive," "We have tons of homework," and "I love you a ton."

==History==
The ton is derived from the ''[[Tun (volume)|tun]]'', the term applied to a cask of the largest capacity. This could contain a volume between {{convert|175|and|213|impgal|USgal l|lk=on}}, which could weigh around {{convert|2,000|lb|kg|lk=on}}, and occupy some {{convert|60|cuft|m3|lk=on}} of cargo space.<ref name=BTS.GOV>{{cite web |url=http://ntl.bts.gov/DOCS/narmain/narmain.html |title=Naval Architecture for All |publisher=United States Bureau of Transportation Statistics |access-date=October 13, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20081010071508/http://ntl.bts.gov/DOCS/narmain/narmain.html |archive-date=October 10, 2008 }}. "Historically, a very important and standard cargo for European sailing vessels was wine, stored and shipped in casks called tuns. These tuns of wine, because of their uniform size and their universal demand, became a standard by which a ship's capacity could be measured. A tun of wine weighed approximately 2,240 pounds, and occupied nearly 60 cubic feet." ([[Thomas C. Gillmer|Gillmer, Thomas]] (1975). ''Modern Ship Design''. United States Naval Institute.) "Today the ship designers standard of weight is the long ton which is equal to 2,240 pounds." This is the weight of 35 cubic feet of Sea Water at a specific gravity of 1.025, compared to Fresh Water, specific gravity of 1.000 usually measured at 60 degrees F. Handy numbers: 35, 36, 37, number of Cubic Feet per Salt Water, Fresh Water and Lube Oil.</ref>

==Units of mass/weight==
There are several similar units of [[mass]] or volume called the '''ton''':

{| class="wikitable"
!Full name(s)
!Common name
!Quantity{{efn|Conversions are exact unless otherwise stated.}}
!Symbol
!width=400|Notes
|-
|[[long ton]]<ref>{{cite web |url=http://www.msc.navy.mil/msfsc/glossary.htm |title=Definitions, Tonnages and Equivalents |website=Military Sealift Fleet Support Command |access-date=2012-12-12 |url-status=dead |archive-url=https://web.archive.org/web/20130516154654/http://www.msc.navy.mil/msfsc/glossary.htm |archive-date=2013-05-16 }}</ref>
|"ton" (United Kingdom)
|{{convert|2,240|lb|kg|sigfig=11|abbr=on|lk=on}}
|LT
|Used in Ireland and [[Commonwealth of Nations|Commonwealth]] countries that formerly used, or still use the [[Imperial unit|Imperial system]]
|-
|[[short ton]]<ref>{{cite web|url=http://ts.nist.gov/WeightsAndMeasures/Publications/appxc.cfm |title=General Tables of Units of Measurement |orig-date=November 11, 2000 |date=April 19, 2006 |website=NIST |access-date=2013-07-01 |url-status=dead |archive-url=https://web.archive.org/web/20111210164956/http://ts.nist.gov/weightsandmeasures/publications/appxc.cfm |archive-date=2011-12-10 }}</ref>
|"ton" (United States)
|{{convert|2,000|lb|kg|sigfig=8|abbr=on}}
|tn<ref name=NIST44-C>
{{cite web
  | url         = https://www.nist.gov/system/files/documents/2023/01/30/appc-23-HB44.pdf
  | title       = NIST Handbook 44 Specifications: Handbook 44 – 2023 Appendix C – General Tables of Units of Measurement
  | page        = C-7
  | date        = November 18, 2022
  | access-date  = May 9, 2023
  | quote       = 20 hundredweights = 1 ton
}}</ref> or st<ref>
{{cite web |url=https://dictionary.cambridge.org/dictionary/english/short-ton  |title=Meaning of short ton in English |website=Cambridge Dictionary |access-date=May 26, 2023}}</ref> 
|Used in the United States and in some industries in Canada
|-
|[[tonne]]<ref name="si2019">{{SIbrochure9th}}</ref><br>(equivalent to one [[megagram]])
|"tonne";<br>"metric ton"
|1,000&nbsp;kg (about 2,204.6226&nbsp;lb)
|t<ref name="si2019">{{SIbrochure9th}}</ref> 
| Defined in the [[International System of Units]]. Used worldwide.
|-
|shortweight ton{{refn|The longweight and shortweight tons were used as a means of making an allowance for wastage in an industrial process. The workman is provided with a longweight ton and is expected to return a shortweight ton of processed product. These measures were particularly used in the operation of hammering iron blooms into shape.<ref>Chris Evans, Göran Rydén, ''Baltic iron in the Atlantic world in the eighteenth century'', p.257, Brill 2007 {{ISBN|90-04-16153-8}}</ref>|name=longshortweight|group=lower-alpha}}
|
|2,240&nbsp;lb
|
|rowspan=2|Used in the iron industry in the 17th and 18th centuries.
|-
|longweight ton<ref name="longshortweight" group="lower-alpha"/>
|
|2,400&nbsp;lb{{refn|In other industries, a different longweight ton might be used. Coal miners delivered coal to the surface in longweight tons, but were paid only for a shortweight ton. This was supposedly to allow for "dirt" (non-coal rocks) in the output. Mine owners, however, were free to set the value of the longweight ton at a value of their own choosing, and in at least some cases, it was set to {{nowrap|25 [[Centum weight|cwt]]}} ({{nowrap|2,800 lb}}) compared to the {{nowrap|20 cwt}} shortweight ton. This was a source of discontent amongst the miners who saw the practice as unfair in favour of the mine owners.<ref>"Report of the select committee on mines", ''Reports from Committees 1866'', '''vol.9''', pp.134-136, London: House of Commons, 23 July 1866</ref>|name=altlongweight|group=lower-alpha}}
|
|}

{{notelist|}}

The difference between the short ton and the other common forms ("long" and "metric") is about 10%, while the metric and long tons differ by less than 2%.

The metric tonne is usually distinguished by its spelling when written, but in the United States and United Kingdom, it is pronounced the same as ton, hence is often spoken as "metric ton" when it is necessary to make the distinction. In the United Kingdom the final "e" of "tonne" can also be pronounced ({{IPAc-en|ˈ|t|ʌ|n|i}}).<ref name="oedtonne">{{cite OED|tonne}}</ref> In Australia, it is pronounced {{IPAc-en|t|ɒ|n}}.

In Ireland and most members of the Commonwealth of Nations, a ton is defined as {{convert|2,240|lb|kg|5}}.{{efn|The "pound" used in this article is the [[avoirdupois pound]]. Its mass [[International yard and pound|is defined]] as exactly 0.45359237 kg  }}<ref>{{cite web| url = http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf| title = Weights and Measures Act 1985| access-date = 2010-02-03| date = 1985-10-30| publisher = Her Majesty's Stationery Office| url-status = live| archive-url = https://web.archive.org/web/20091208083258/http://www.opsi.gov.uk/acts/acts1985/pdf/ukpga_19850072_en.pdf| archive-date = 2009-12-08}}</ref>

In the United States and Canada,<ref name=Canada>{{cite web|url=http://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont|title=Weights and Measures Act: Canadian units of measure, Schedule II (Section 4)|publisher=Department of Justice|access-date=2011-07-06|url-status=live|archive-url=https://web.archive.org/web/20110811094412/http://laws-lois.justice.gc.ca/eng/acts/W-6/page-10.html#docCont|archive-date=2011-08-11}}</ref> a ton is defined as {{convert|2000|lb|kg|5}}.

===Other units of mass/weight===
*'''[[Deadweight tonnage|Deadweight ton]]''' (abbreviation 'DWT' or 'dwt') is a measure of a ship's carrying capacity, including bunker oil, fresh water, ballast water, crew, and provisions. It is expressed in tonnes ({{convert|1,000|kg|lb|0}}) or long tons ({{convert|2,240|lb|kg|0}}). This measurement is also used in the U.S. tonnage of naval ships.
* Increasingly, '''[[tonne]]s''' are being used rather than long tons in measuring the [[Displacement (ship)|displacement of ships]].
*'''Harbour ton''', used in South Africa in the 20th century, was equivalent to ({{convert|2,000|lb|kg|0}}) or 1 short ton.

{{anchor|Assay ton}}
'''Assay ton''' (abbreviation 'AT') is not a unit of measurement but a standard quantity used in [[assay]]ing ores of precious metals. A '''short assay ton''' is approximately {{convert|29.16666|g|abbr=on|adj=ri2|3}} and a '''long assay ton''' is approximately {{convert|32.66666|g|abbr=on|adj=ri2|3}}.<ref>{{Cite book |last=Fenna |first=Donald |title=A Dictionary of Weights, Measures, and Units |publisher=Oxford University Press |year=2002 |isbn=9780198605225 |location=Oxford |at=assay ton}}</ref>{{citation needed|reason=though the different US/UK values are attested, the terms "short" and "long" with "assay ton" seem only to be found in Wikipedia/Wiktionary and derivative online convertors|date=August 2023}} These amounts bear the same ratio to a milligram as a short or long ton bears to a [[troy ounce]]. Therefore, the number of milligrams of a particular metal found in a sample weighing one assay ton gives the number of troy ounces of metal contained in a ton of ore.

In documents that predate 1960 the word ''ton'' is sometimes spelled ''tonne'',{{citation needed|reason=No entry for tonne in SOED|date=June 2018}} but in more recent documents ''tonne'' refers exclusively to the [[metric ton]].

In [[nuclear power plant]]s '''tHM''' and '''MTHM''' mean tonnes of [[heavy metals]], and '''MTU''' means tonnes of [[uranium]]. In the [[steel]] industry, the abbreviation '''THM''' means 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced, particularly in the context of [[blast furnace]] production or specific consumption.

{{vanchor|Dry ton|Dry tonne|Wet ton|Wet tonne|text=A '''dry ton''' or '''dry tonne''' has the same mass value, but the material ([[sludge]], slurries, [[compost]], and similar mixtures in which solid material is soaked with or suspended in [[water]]) has been dried to a relatively low, consistent [[moisture]] level ([[dry weight]]). If the material is in its natural, wet state, it is called a '''wet ton''' or '''wet tonne'''.}}

===Subdivisions===
Both the UK definition of long ton and US definition of short ton have similar underlying bases. Each is equivalent to 20 hundredweight; however, they are [[long hundredweight|long]] {{convert|112|lb|kg}} and [[short hundredweight|short]] {{convert|100|lb|kg}} hundredweight, respectively.

Before the 20th century there were several definitions. Prior to the 15th century in England, the ton was 20&nbsp;hundredweight, each of 108&nbsp;lb, giving a ton of {{convert|2160|lb|kg}}.{{Citation needed|date=October 2009}}  In the 19th century in different parts of Britain, definitions of 2,240, or 2,352, or 2,400&nbsp;lb were used, with 2,000&nbsp;lb for explosives; the legal ton was usually 2,240&nbsp;lb.<ref>Definitions of 2,000, 2,240, 2,352, and 2,400 lb are included in citations listed in the Oxford English Dictionary, 2nd ed. OED cites an 1858 dictionary of trade products "the legal ton by weight is usually 20 cwt".</ref>

In the United Kingdom, Canada, Australia, and other areas that had used the imperial system, the tonne is the form of ton legal in trade.

==Units of volume==
{{See also|Tonnage}}
The [[Displacement (ship)|displacement]], essentially the weight, of a ship is traditionally expressed in [[long ton]]s.<ref>{{Cite web|last=DesVergers|first=Jake|title=Rules of the Road: Tricky tonnage measurement not about weight|url=https://www.the-triton.com/2017/10/rules-of-the-road-tricky-tonnage-measurement-not-about-weight/|access-date=2021-04-23|website=The Triton|language=en-US}}</ref> To simplify measurement it is determined by measuring the [[volume]], rather than weight, of water displaced, and calculating the weight from the volume and density.<ref>[https://books.google.com/books?id=vylCkqTg7H0C&pg=PA249 Displacement ton] Dictionary of international trade retrieved 22July2010</ref>
For practical purposes the '''displacement ton''' (DT) is a unit of volume, {{convert|35|cuft|sigfig=4}}, the approximate volume occupied by one ton of [[seawater]] (the actual volume varies with salinity and temperature).<ref>[http://www.oxfordreference.com/views/ENTRY.html?entry=t135.e351&srn=1&ssid=351170645#FIRSTHIT A Dictionary of Weights, Measures, and Units, Donald Fenna, 2002] {{ISBN|0-19-860522-6}}</ref> It is slightly less than the 224 imperial gallons (1.018&nbsp;m<sup>3</sup>) of the '''water ton''' (based on [[distilled water]]).

One '''[[Shipping ton|measurement ton]]''' or '''freight ton''' is equal to {{convert|40|cuft|sigfig=4}}, but historically it has had several different definitions. It is used to determine the amount of money to be charged in loading, unloading, or carrying different sorts of cargo. In general if a cargo is heavier than salt water, the actual weight is used. If it is lighter than salt water, e.g. feathers, freight is calculated in measurement tons of 40 cubic feet.<ref>{{cite web |url=http://www.msc.navy.mil/annualreport/2003/financial.htm |title=MSC 2003 in Review - Financial and Statistical Review |publisher=Msc.navy.mil |date=2003-09-30 |access-date=2010-07-31 |url-status=dead |archive-url=https://web.archive.org/web/20110722195701/http://www.msc.navy.mil/annualreport/2003/financial.htm |archive-date=2011-07-22 }}</ref><ref>{{cite web|url = https://www.ustranscom.mil/dbw/docs/FY18_Liner_Breakbulk_and_Container_Rates_and_Guidance.pdf|publisher = Military Surface Deployment and Distribution Command|title = Liner Ocean Transportation Program Stabilized Breakbulk/Dry Cargo and Container Billing Rates|date = 2018}}</ref><ref>{{cite web |url=http://bulk.resource.org/courts.gov/c/F2/182/182.F2d.916.235.21638.html |title=182 F.2d 916 |publisher=Bulk.resource.org |access-date=2010-07-31 |url-status=dead |archive-url=https://web.archive.org/web/20110727214911/http://bulk.resource.org/courts.gov/c/F2/182/182.F2d.916.235.21638.html |archive-date=2011-07-27 }}</ref><ref>{{cite web |url=http://www.stocktonport.com/TERMINAL%20TARIFF/POS%20DEFINITIONS%20GENERAL%20RULES%20AND%20REGULATIONS%20ttariffI.htm |title=Pos Ttariff General Definitions |publisher=Stocktonport.com |access-date=2010-07-31 |url-status=live |archive-url=https://web.archive.org/web/20110716144906/http://www.stocktonport.com/TERMINAL%20TARIFF/POS%20DEFINITIONS%20GENERAL%20RULES%20AND%20REGULATIONS%20ttariffI.htm |archive-date= 2011-07-16 }}</ref>

'''[[Gross tonnage]]''' and '''[[net tonnage]]''' are volumetric measures of the cargo-carrying capacity of a ship.

The '''Panama Canal/Universal Measurement System (PC/UMS)''' is based on [[net tonnage]], modified for Panama Canal billing purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; a '''PC/UMS net ton''' is equivalent to 100 cubic feet of capacity.<ref>[http://www.pancanal.com/eng/general/peajes-en-el-canal.html ''Panama Canal Tolls''] {{webarchive|url=https://web.archive.org/web/20080916113752/http://www.pancanal.com/eng/general/peajes-en-el-canal.html |date=2008-09-16 }}, [[Panama Canal Authority]]. Retrieved 10 May 2006.</ref>

The '''water ton''' is used chiefly in Great Britain, in statistics dealing with petroleum products, and is defined as {{convert|224|impgal|cuft m3|sigfig=4}},<ref>{{cite web|url=https://www.nist.gov/pml/wmd/pubs/upload/AppB-12-hb44-final.docx|title=NIST: Units and Systems of Measurement Their Origin, Development, and Present Status|website=nist.gov|access-date=1 May 2018|url-status=live|archive-url=https://web.archive.org/web/20160616205300/http://www.nist.gov/pml/wmd/pubs/upload/AppB-12-hb44-final.docx|archive-date=16 June 2016}}</ref> the volume occupied by {{convert|1|long ton|lb kg|0}} of water under the conditions that define the [[imperial units|imperial]] [[gallon]].

==Colloquial English==
*'''Ton''' is also used informally, often as [[slang]], to mean a large amount of something.<ref>Merriam-Webster's English Dictionary defines ton as: "a great quantity". [https://www.merriam-webster.com/dictionary/ton]</ref>
*In [[United Kingdom|Britain]], a ton is colloquially used to refer to 100 of a given unit. Ton can thus refer to a speed of 100 miles per hour, and is prefixed by an indefinite article, e.g. "Lee was doing a ton down the motorway"; to money e.g. "How much did you pay for that?" "A ton" (£100); to 100 points in a game e.g. "Eric just threw a ton in our darts game" (in some games, e.g. [[cricket]], more commonly called a century); or to a hundred of any other countable figure.<ref>Colin R. Chapman, ''Weights, Money and Other Measures Used by our Ancestors'', p.93, Genealogical Publishing Com, 1996 {{ISBN|0-8063-1501-6}}.</ref><ref>{{cite book|first = John|last = MacRae-Hall |title =A Deniable Asset|page = 85|publisher = iUniverse|date = 2011|isbn= 9781450280808|url =https://books.google.com/books?id=_MaEhEXt2W8C&pg=PA85}}</ref><ref>The Oxford English Dictionary 2nd ed. lists colloquial use of "ton" from 1946 for £100, and later 100 mph, and for 100 in general.</ref>

==See also==
{{Wiktionary|ton}}
{{Div col}}
*[[Conversion of units]]

*[[English units of measurement|English units]]
*[[Gross ton mile]]
*[[Imperial units]]
*[[Systems of measurement]]
*[[TNT equivalent]]
*[[Ton of refrigeration]]
*[[truck classification]]
*unit of [[energy]]
*[[United States customary units]]
{{colend}}

==References==
{{Notelist}}
{{Reflist}}

{{Imperial units}}
{{United States Customary Units}}

[[Category:Units of mass]]
[[Category:Units of volume]]
[[Category:Customary units of measurement in the United States]]
[[Category:Imperial units]]