# Cubic inch

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Cubic inch
An engine with a swept piston displacement of 502 cubic inches.
General information
Unit system Nonstandard
Unit ofvolume
Symbolin3orcu in
Conversions
1 in3in ...... is equal to ...
SI derived units    16.387  mL
US customary    1231  US Gallon
nonstandard   11728  ft3

The cubic inch (symbol in3) 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 depth) being one inch long which is equivalent to 1/231 of a US gallon. 

## Contents

The cubic inch and the cubic foot are used as units of volume in the United States, although the common SI units of volume, the liter, milliliter, and cubic meter, are also used, especially in manufacturing and high technology. One cubic inch is approximately 16.387  mL .

One cubic foot is equal to exactly 1,728 cubic inches because 123 = 1,728.

One U.S. gallon is equal to exactly 231 cubic inches because 3 * 7 * 11 = 231.[ dubious ]

## 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: in³
• In internal combustion engines, the following abbreviations are used to denote cubic inch displacement: c.i.d., cid, CID, c.i., ci

## Equivalence with other units of volume

1 cubic inch (assuming an international inch) is equal to:

• 0.000578703703703 cubic feet (1  cu ft equals 1,728 cu in)
• roughly 1 tablespoon (1.0 U.S. gallon = 256 U.S. tablespoons = 231 cubic inches)
• about 0.554112552 American/English fluid ounces
• about 0.004329 American liquid gallons (1.0 gallon equals 231 cu in exactly [3 in × 7 in × 11 in])
• about 0.00010307 barrels of crude oil (1.0 barrel equals 42 gallons, by definition, or 9,702 cu in)
• exactly 0.016387064 liter (1.0 liter is about 61 cu in [exactly 61.0237440947323 cu in])
• exactly 16.387064 milliliters or cubic centimeters (which in turn is approximately 0.061 cu in)
• exactly 0.000016387064 cubic meters (1.0 m³ is about 61,023.74 cu in)

## Uses of the cubic inch

### Electrical box volume

The cubic inch was established decades ago 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 and aircraft industry in North America (through the early 1980s) to express the nominal engine displacement for the engines of new automobiles, trucks, aircraft, etc. The cubic inch is still used for this purpose in classic car collecting. The auto industry now uses 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 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 Corvette. Dodge has a "Challenger 392" (a conversion from its 6.4 liter V8 engine).

#### United Kingdom

In the UK, engine displacement is now denoted in litres. However, cubic inches were sometimes used in the past to denote model numbers. An example is the AEC Reliance bus which was available with five different engines:

• AH470, 470 cubic inches, 7.7 litres = 1.6942 gallons
• AH505, 505 cubic inches, 8.1 litres = 1.8203 gallons
• AH590, 590 cubic inches, 9.6 litres = 2.1267 gallons
• AH691, 691 cubic inches, 11.3 litres = 3.5925 gallons
• AH760, 760 cubic inches, 12.4 litres = 3.9512 gallons

## Related Research Articles

The density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: The litre or liter is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). A cubic decimetre occupies a volume of 10 cm × 10 cm × 10 cm and is thus equal to one-thousandth of a cubic metre. United States customary units form a system of measurement units commonly used in the United States and U.S. territories since being formalized in 1832. The United States customary system developed from English units which were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures was overhauled in 1824 to create the imperial system, which was officially adopted in 1826, changing the definitions of some of its units. Subsequently, while many U.S. units are essentially similar to their imperial counterparts, there are significant differences between the systems. Volume is the quantity of three-dimensional space enclosed by a closed surface. For example, the space that a substance or 3D shape occupies or contains. Volume is often quantified numerically using the SI derived unit, the cubic metre. The volume of a container is generally understood to be the capacity of the container; i.e., the amount of fluid that the container could hold, rather than the amount of space the container itself displaces. Three dimensional mathematical shapes are also assigned volumes. Volumes of some simple shapes, such as regular, straight-edged, and circular shapes can be easily calculated using arithmetic formulas. Volumes of complicated shapes can be calculated with integral calculus if a formula exists for the shape's boundary. One-dimensional figures and two-dimensional shapes are assigned zero volume in the three-dimensional space. In recipes, quantities of ingredients may be specified by mass, by volume, or by count. A cubic centimetre is a commonly used unit of volume that corresponds to the volume of a cube that measures 1 cm x 1 cm × 1 cm. One cubic centimetre corresponds to a volume of one millilitre. The mass of one cubic centimetre of water at 3.98 °C is almost equal to one gram. Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the power an engine might be capable of producing and the amount of fuel it should be expected to consume. For this reason displacement is one of the measures often used in advertising, as well as regulating, motor vehicles. The pint is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems it is traditionally one eighth of a gallon. The British imperial pint is about 20% larger than the American pint because the two systems are defined differently. Almost all other countries have standardized on the metric system, so the size of what may be called a pint, from the French la pinte, varies depending on local custom.

The cubic foot is an imperial and US customary (non-metric) unit of volume, used in the United States and the United Kingdom. It is defined as the volume of a cube with sides of one foot in length. Its volume is 28.3168 L.

The quart is an English unit of volume equal to a quarter gallon. Three kinds of quarts are currently used: the liquid quart and dry quart of the US customary system and the imperial quart of the British imperial system. All are roughly equal to one liter. It is divided into two pints or four cups. Historically, the exact size of the quart has varied with the different values of gallons over time and in reference to different commodities. A fluid ounce is a unit of volume typically used for measuring liquids. Various definitions have been used throughout history, but only two are still in common use: the British Imperial and the United States customary fluid ounce. A barrel is one of several units of volume applied in various contexts; there are dry barrels, fluid barrels, oil barrels, and so forth. For historical reasons the volumes of some barrel units are roughly double the volumes of others; volumes in common use range approximately from 100 to 200 litres. In many connections the term drum is used almost interchangeably with barrel. Metrication is the process of introducing the International System of Units, also known as SI units or the metric system, to replace a jurisdiction's traditional measuring units. Although U.S. customary units have been defined in terms of metric units since the 19th century, as of 2021 the United States is one of only three countries that have not officially adopted the metric system as the primary means of weights and measures. A dessert spoon is a spoon designed specifically for eating dessert and sometimes used for soup or cereals. Similar in size to a soup spoon but with an oval rather than round bowl, it typically has a capacity around twice that of a teaspoon.

The tun is an English unit of liquid volume, used for measuring wine, oil or honey. Typically a large vat or vessel, most often holding 252 wine gallons, but occasionally other sizes were also used. Both the British Imperial and United States customary systems of measurement derive from earlier English systems used in the Middle Ages, that were the result of a combination of the local Anglo-Saxon units inherited from Germanic tribes and Roman units brought by William the Conqueror after the Norman Conquest of England in 1066. The cubic metre or cubic meter is the SI derived unit of volume. Its SI symbol is m3. It is the volume of a cube with edges one metre in length. An alternative name, which allowed a different usage with metric prefixes, was the stère, still sometimes used for dry measure. Another alternative name, no longer widely used, was the kilolitre. The imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.

1. "260.1-2004 - IEEE Standard Letter Symbols for Units of Measurement (SI Customary Inch-Pound Units, and Certain Other Units)". standards.ieee.org. Retrieved 22 December 2019.