A 'cubic inch' (plural: 'cubic inches') is a non-
SI unit of
volume, equal to the volume of a
cube with sides of one
inch.
Cubic inches are still sometimes used as a unit of measurement (in engineering contexts, not household contexts) in the
United States and
United Kingdom, although SI is continuing gradually to displace non-SI usage.
Notation conventions
The following symbols are used to denote cubic inches:
★ cubic in
★ cu inches, cu inch, cu in
★ inches/-3, inch/-3, in/-3
★ inches^3, inch^3, in^3
★ inches³ ,inch³, in³
★ c.i.
★ c.i.d. or
CID, for cubic inch
displacement, in
internal combustion engines
Equivalence with other units of volume
1 cubic inch (assuming an international
inch) is equal to:
★ 0.000578703703703
cubic feet (1 ft³ equals 1,728 in³)
★ about 0.554112552 U.S.
fluid ounces
★ about 0.069264069 U.S.
cups
★ about 0.000465025413 U.S.
bushels
★ about 0.004329 U.S. liquid
gallons (1 gallon equals 231 in³)
★ about 0.00010307 crude
barrels (1 barrel equals 42 gallons, or 9702 in³)
★ exactly 0.016387064
litres (1 L is about 61 in³)
★ exactly 16.387064 millilitres or
cubic centimetres (which in turn are about 0.061 in³)
★ exactly 0.000016387064
cubic metres (1 m³ is about 61,023.75 in³)
Uses of the cubic inch
Electrical box volume
The cubic inch was established decades ago as the conventional unit in the U.S. for measuring the volume of electrical boxes; SI has not yet replaced it for this purpose.
Engine displacement
The cubic inch was formerly used (until the 1980s) to express the size (displacement) of engines for new cars, trucks, etc. It is therefore still used for this purpose in the context of the classic-car hobby, auto racing, and so forth. (The auto industry nowadays uses
SI for this purpose.) Some examples of common c.i.-to-litre conversions are given below. Note that nominal sizes are not always precisely equal to actual sizes. This principle is frequently seen in engineering, tool standardization, etc. (for ease of use) and in marketing (when a big round number sounds more impressive, is more memorable, etc.).
| Make (±Division) | c.i. (actual) (nearest 1) | c.i. (nominal) | SI (actual) (nearest 0.01) | SI (nominal) |
|---|
| Honda, Kawasaki, others | something close to 61 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 1000 cc (= 1.0 L) |
| Honda, Kawasaki, others | something close to 98 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 1600 cc (= 1.6 L) |
| Honda, Kawasaki, others; Ford | something close to 122 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 2000 cc (= 2.0 L) |
| GM (Pontiac, Buick, Oldsmobile, GMC, others) | 151 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 2.5 L |
| Toyota, Ford, Chrysler, others | something close to 183 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 3.0 L |
| Ford | something close to 244 c.i. | NA (not marketed in c.i.) | [something close to SI nominal] | 4.0 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 250 c.i. | 4.10 L | 4.1 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 289 c.i. | 4.74 L | NA (not marketed in SI) |
| Ford (Ford trucks and vans) | [something close to c.i. nominal] | 300 c.i. | 4.92 L | 4.9 L |
| Ford, GM (Chevrolet) | [something close to c.i. nominal] | 302 c.i. | 4.95 L | 5.0 L |
| GM (Chevrolet; others?) | 307 c.i. | 307 c.i. | 5.03 L | NA (not marketed in SI) |
| GM (Oldsmobile) | 307 c.i. | NA (not marketed in c.i.) | 5.03 L | 5.0 L |
| GM (GMC, Chevrolet, Buick, Oldsmobile, Pontiac, others) | [something close to c.i. nominal] | 350 c.i. | 5.74 L | 5.7 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 351 c.i. | 5.75 L | NA (not marketed in SI) |
| Chrysler (Chrysler, Dodge, Plymouth) | [something close to c.i. nominal] | 360 c.i. | 5.90 L | 5.9 L |
| Chrysler (Chrysler, Dodge, Plymouth) | [something close to c.i. nominal] | 383 c.i. | 6.28 L | NA (not marketed in SI) |
| GM (Chevrolet) | [sometimes 396 c.i., sometimes 402 c.i.] | 396 c.i. | 6.49 L | NA (not marketed in SI) |
| GM (Chevrolet) | [something close to c.i. nominal] | 409 c.i. | 6.70 L | NA (not marketed in SI) |
| Chrysler (Chrysler, Dodge, Plymouth) | [something close to c.i. nominal] | 426 c.i. | 6.98 L | 7.0 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 427 c.i. | 7.00 L | 7.0 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 428 c.i. | 7.01 L | 7.0 L |
| Ford (Ford, Mercury) | [something close to c.i. nominal] | 429 c.i. | 7.03 L | 7.0 L |
| Chrysler (Chrysler, Dodge, Plymouth) | [something close to c.i. nominal] | 440 c.i. | 7.21 L | 7.2 L |
| GM (GMC, Chevrolet) | [something close to c.i. nominal] | 454 c.i. | 7.44 L | 7.4 L |
| GM (Buick, Oldsmobile, Pontiac) | [something close to c.i. nominal] | 455 c.i. | 7.46 L | NA (not marketed in SI) |
| Ford (Ford [trucks and vans]; Lincoln [cars]) | [something close to c.i. nominal] | 460 c.i. | 7.54 L | 7.5 L |
| GM (Cadillac) | [something close to c.i. nominal] | 472 c.i. | 7.73 L | 7.7 L |
| GM (Cadillac) | [something close to c.i. nominal] | 500 c.i. | 8.19 L | 8.2 L |
See also
★
1 E-2 m³ for a comparison with other volumes
★
Orders of magnitude (volume)
★
Conversion of units
★
Square inch
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