What is a Cubic Inch?

The cubic inch equals exactly 16.387064 cubic centimeters and is the traditional American unit for engine displacement and small-volume manufacturing measurements. Classic American muscle cars were famously identified by their cubic-inch engine size: the Ford 'Boss 429' had a 429-cubic-inch (7.0-liter) V8, and the Chevrolet 'Big Block 454' was 7.4 liters. Modern American automakers have transitioned mostly to liter-based naming (e.g., 'Hemi 5.7'), but the cubic inch persists in vintage car culture and aviation engines. It is also used for printer-paper coverage and industrial tolerances. The cubic inch relates to the cubic foot (1,728 in³ = 1 ft³), the cubic centimeter (1 in³ ≈ 16.39 cm³), the milliliter (1 in³ ≈ 16.39 mL), and the US fluid ounce (1 fl oz ≈ 1.805 in³).

Visual reference for how the cubic inch relates to other volume units. Each row links to the full converter for that pair.

See all 15 volume units in matrix view →

• Classic US car engine displacement
• Firearms chamber and cartridge specs
• Some US machining and mould design

• ✓1 in³ = 16.387 cm³ exactly.
• ✓To convert cubic inches to litres, divide by 61.02.
• ✓US automotive ads today quote both cu in and L for classic cars.

• ✗Confusing in³ with in² or linear inches.
• ✗Using 16 instead of 16.387 on precision machining.
• ✗Assuming modern European engines are marked in cu in — they are always in L or cc.