The cubic inch (symbol in³) is a

unit of volume A unit of volume is a unit of measurement for measuring volume or capacity, the extent of an object or space in three dimension (mathematics), dimensions. Units of capacity may be used to specify the volume of fluids or bulk goods, for example wat ...

in the

Imperial units The imperial system of units, imperial system or imperial units (also known as British Imperial or Exchequer Standards of 1826) is the system of units first defined in the British Weights and Measures Act 1824 and continued to be developed thr ...

and

United States customary units United States customary units form a system of measurement units commonly used in the United States and most U.S. territories since being standardized and adopted in 1832. The United States customary system developed from English units that ...

systems. It is the volume of a

cube A cube or regular hexahedron is a three-dimensional space, three-dimensional solid object in geometry, which is bounded by six congruent square (geometry), square faces, a type of polyhedron. It has twelve congruent edges and eight vertices. It i ...

with each of its three dimensions (length, width, and height) being one

inch The inch (symbol: in or prime (symbol), ) is a Units of measurement, unit of length in the imperial units, British Imperial and the United States customary units, United States customary System of measurement, systems of measurement. It is eq ...

long which is equivalent to of a US gallon. The cubic inch and the

cubic foot The cubic foot (symbol ft3 or cu ft)
, . is an United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, although the common SI units of volume, the

liter The litre ( Commonwealth spelling) or liter ( American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A cu ...

milliliter The litre (Commonwealth English, Commonwealth spelling) or liter (American English, American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric units, metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic c ...

, and

cubic meter The cubic metre (in Commonwealth English and international spelling as used by the International Bureau of Weights and Measures) or cubic meter (in American English) is the unit of volume in the International System of Units (SI). Its symbol is m ...

, are also used, especially in

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary sector of the economy. The term may refer ...

and

high technology High technology (high tech or high-tech), also known as advanced technology (advanced tech) or exotechnology, is technology that is at the cutting edge: the highest form of technology available. It can be defined as either the most complex or ...

. One cubic inch is exactly . One cubic foot is equal to exactly , as 12³ = 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 The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) organization, 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines. The IEEE ...

standard symbol is: in³ * In

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

s, the following abbreviations are used to denote cubic inch

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

: c.i.d., cid, CID, c.i., ci

Equivalence with other units of volume

One cubic inch is equal to: * Exactly cubic feet * Exactly US gallon * Exactly US liquid quart * Exactly US liquid pint * Exactly US gill * Exactly US fluid ounce * Exactly US

tablespoon A tablespoon (tbsp., Tbsp., Tb., or T.) is a large spoon. In many English-speaking regions, the term now refers to a large spoon used for serving; however, in some regions, it is the largest type of spoon used for eating. By extension, the ter ...

s * Exactly US

teaspoon A teaspoon (tsp.) is a small spoon that can be used to stir a cup of tea or coffee, or as a tool for measuring volume. The size of teaspoons ranges from about . For dosing of medicine and, in places where metric units are used, for cooking pu ...

s * Exactly US fluid drams * Exactly US bushel * Exactly US dry quart * Exactly 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 barrel of crude oil * Exactly

Uses of the cubic inch

Electrical box volume

The cubic inch was established decades ago in the

National Electrical Code The National Electrical Code (NEC), or NFPA 70, is a regionally adoptable standard for the safe installation of electrical wiring and equipment in the United States. It is part of the National Fire Code series published by the National Fire Prote ...

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

North America

The cubic inch was formerly used by the

automotive industry The automotive industry comprises a wide range of company, companies and organizations involved in the design, Business development, development, manufacturing, marketing, selling, Maintenance, repairing, and Custom car, modification of motor ve ...

and

aircraft industry An aircraft ( aircraft) is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, direct downward thrust from its e ...

in North America (through the early 1980s) to express the nominal engine displacement for the engines of new

automobile A car, or an automobile, is a motor vehicle with wheels. Most definitions of cars state that they run primarily on roads, Car seat, seat one to eight people, have four wheels, and mainly transport private transport#Personal transport, peopl ...

truck A truck or lorry is a motor vehicle designed to transport freight, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construct ...

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

, etc. The cubic inch is still used for this purpose in classic car collecting. The auto industry now uses

liters The litre ( Commonwealth spelling) or liter (American spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metres (m3). A cubic ...

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 The Ford Mustang is a series of American Car, automobiles manufactured by Ford Motor Company, Ford. In continuous production since 1964, the Mustang is currently the longest-produced Ford car nameplate. Currently in its Ford Mustang (seventh ...

has a Boss 302 version that reflects this heritage - with a five-liter (302 cubic inch) engine similar to the original Boss.

Chevrolet Chevrolet ( ) is an American automobile division of the manufacturer General Motors (GM). In North America, Chevrolet produces and sells a wide range of vehicles, from subcompact automobiles to medium-duty commercial trucks. Due to the promi ...

has also revived this usage on its 427

Corvette A corvette is a small warship. It is traditionally the smallest class of vessel considered to be a proper (or " rated") warship. The warship class above the corvette is that of the frigate, while the class below was historically that of the sloo ...

Dodge Dodge is an American brand of automobiles and a division of Stellantis, based in Auburn Hills, Michigan. Dodge vehicles have historically included performance cars, and for much of its existence, Dodge was Chrysler's mid-priced brand above P ...

has a "Challenger 392" (a conversion from its 6.4 liter V8 engine).

References

{{United States Customary Units Customary units of measurement in the United States Imperial units Units of volume ja:インチ#立方インチ