Convert Cubic Inch to Fluid Ounce (in³ → fl oz)

Converting cubic inches to fluid ounces is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in cubic inches

   Start with the number of cubic inches (in³) you want to convert.
2. 2
   Multiply by 0.554113

   The conversion factor from in³ to fl oz is 0.554113. Multiply your value by this number.
3. 3
   Read the result in fluid ounces

   The result is your value in fluid ounces (fl oz).

Multiply the value in cubic inches by 0.554113. For the reverse direction, multiply by 1.804688.

• ✓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.

What is the 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).

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

What is the Fluid Ounce?

The US fluid ounce equals exactly 29.5735295625 milliliters and is the standard small-volume unit for beverages, cocktails, personal-care products, and cooking in the United States. It is distinct from the (weight) ounce: 1 fluid ounce of water weighs about 1 ounce by weight at room temperature, but other liquids may weigh more or less. Soft-drink cans (12 fl oz), beer bottles (12 fl oz), shampoo bottles, and skin-cream tubs all label volume in fluid ounces. The US fluid ounce is slightly different from the UK imperial fluid ounce (28.4131 mL — about 4% smaller), reflecting the different gallon definitions. The US fl oz relates to the gallon (128 fl oz = 1 gal), the cup (8 fl oz = 1 cup), the tablespoon (2 tbsp = 1 fl oz), and the milliliter (1 fl oz ≈ 29.57 mL). Cocktail recipes universally use fluid ounces.

• US beverage and soda can sizes (12 fl oz)
• Cosmetic and personal-care product volumes
• US fluid recipes and cocktail measures