View source for Cubic inch

{{Short description|Unit of volume}}
{{Use American English|date=February 2023}}
{{Use mdy dates|date=February 2023}}
{{More citations needed|date=February 2022}}
{{Infobox unit
| name     = Cubic inch
| image    = Chevy502CID.jpg
| caption  = An engine with a swept piston [[Engine displacement|displacement]] of 502 cubic inches
| standard = Nonstandard
| quantity = volume
| symbol   = in<sup>3</sup>
| symbol2  = cu in
| units1   = [[SI derived unit]]s
| inunits1 = {{val|16.387064|ul=mL}}
| units2   = [[United States customary units|US customary]]
| inunits2 = {{sfrac|231}}&nbsp;[[US gallon]]
| units3   = nonstandard
| inunits3 = {{sfrac|1728}}&nbsp;[[cubic feet|ft<sup>3</sup>]]
}}

The '''cubic inch''' (symbol '''in<sup>3</sup>''') is a [[unit of volume]] in the [[Imperial units]] and [[United States customary units]] systems. It is the volume of a [[cube]] with each of its three dimensions (length, width, and height) being one [[inch]] long which is equivalent to {{sfrac|231}} of a US gallon.<ref name="IEEE 260.1-2004">{{cite tech report |title=IEEE Standard Letter Symbols for Units of Measurement (SI Customary Inch-Pound Units, and Certain Other Units) |title-link=IEEE Std 260.1-2004 |institution=IEEE |date=2004 |number=260.1-2004 }}</ref>

The cubic inch and the [[cubic foot]] are used as units of volume in the [[United States]], although the common [[International System of Units|SI]] units of volume, the [[liter]], [[milliliter]], and [[cubic meter]], are also used, especially in [[manufacturing]] and [[high technology]]. One cubic inch is exactly {{val|16.387064|ul=mL}}.

One cubic foot is equal to exactly {{Convert|1728|cuin|L|9}}, as 12<sup>3</sup> = 1728.

==Notation conventions==
* The following abbreviations have been used to denote the cubic inch: cubic in, cu inch, cu in, cui, cu. in.
* The [[IEEE]] standard symbol is: in<sup>3</sup><ref name="IEEE 260.1-2004" />
* In [[internal combustion engine]]s, the following abbreviations are used to denote cubic inch [[Engine displacement|displacement]]: c.i.d., cid, CID, c.i., ci

==Equivalence with other units of volume==
One cubic inch is equal to:
* Exactly {{sfrac|1|1728}} cubic feet
* Exactly {{sfrac|1|231}} US gallon
* Exactly {{sfrac|4|231}} US liquid quart
* Exactly {{sfrac|8|231}} US liquid pint
* Exactly {{sfrac|32|231}} US [[Gill (unit)|gill]]
* Exactly {{sfrac|128|231}} US fluid ounce
* Exactly {{sfrac|1|25|231}} US [[tablespoon]]s
* Exactly {{sfrac|3|25|77}} US [[teaspoon]]s
* Exactly {{sfrac|4|100|231}} US fluid drams
* Exactly {{sfrac|50|107521}} US bushel
* Exactly {{sfrac|1600|107521}} US dry quart
* Exactly {{sfrac|3200|107521}} US dry pint
* ≈0.00360465 imperial gallons
* ≈0.0144186 imperial quarts
* ≈0.0288372 imperial pints
* ≈0.1153488 imperial gills
* ≈0.576744 imperial fluid ounces
* ≈1.153488 imperial tablespoons
* ≈4.613952 imperial fluid drams
* ≈0.00045058 imperial bushels
* Exactly {{sfrac|1|9702}} barrel of crude oil
* Exactly {{convert|1.0000000|in3|mL|disp=out|abbr=off|sp=us}}

==Uses of the cubic inch==

===Electrical box volume===
The cubic inch was established decades ago in the [[National Electrical Code]] as the conventional unit in North America for measuring the volume of electrical boxes. Because of the extensive export of electrical equipment to other countries, some usage of the non-SI unit can be found outside North America.

===Engine displacement===
{{main|Engine displacement}}

====North America====
The cubic inch was formerly used by the [[automotive industry]] and [[aircraft industry]] in North America (through the early 1980s) to express the nominal engine displacement for the engines of new [[automobile]]s, [[truck]]s, [[aircraft]], etc. The cubic inch is still used for this purpose in classic car collecting. The auto industry now uses [[Litre|liters]] for this purpose, while reciprocating engines used in commercial aircraft often have model numbers based on the cubic inch displacement. The fifth generation [[Ford Mustang (fifth generation)|Ford Mustang]] has a Boss 302 version that reflects this heritage - with a five-liter (302 cubic inch) engine similar to the original Boss. [[Chevrolet]] has also revived this usage on its 427 [[Chevrolet Corvette|Corvette]]. [[Dodge]] has a  "Challenger 392" (a conversion from its 6.4 liter V8 engine).

==See also==
* [[Conversion of units]]
* [[Orders of magnitude (volume)]]
* [[Square inch]]

==References==
{{Reflist}}

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

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

[[ja:インチ#立方インチ]]