Convert Cubic Inch to US Gallon (in³ → gal (US))
The cubic inch measures classic American engine displacement and small-volume manufacturing tolerances.
Cubic Inch to US Gallon Conversion Table
10 common values| Cubic Inch | US Gallon |
|---|---|
| 1 in³ | 0.004329 gal (US) |
| 2 in³ | 0.008658 gal (US) |
| 5 in³ | 0.021645 gal (US) |
| 10 in³ | 0.04329 gal (US) |
| 20 in³ | 0.08658 gal (US) |
| 50 in³ | 0.21645 gal (US) |
| 100 in³ | 0.4329 gal (US) |
| 200 in³ | 0.865801 gal (US) |
| 500 in³ | 2.164502 gal (US) |
| 1,000 in³ | 4.329004 gal (US) |
How to Convert Cubic Inch to US Gallon Manually
Step by StepConverting cubic inches to US gallons is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in cubic inchesStart with the number of cubic inches (in³) you want to convert.
- 2Multiply by 0.004329The conversion factor from in³ to gal (US) is 0.004329. Multiply your value by this number.
- 3Read the result in US gallonsThe result is your value in US gallons (gal (US)).
Formula
Multiply the value in cubic inches by 0.004329. For the reverse direction, multiply by 231.
gal (US) = in³ × 0.004329in³ = gal (US) × 231Tips
Use these in everyday conversions- 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.
Common Mistakes
Avoid these- 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.
About Cubic Inch and US Gallon
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
350 cu in V8 = 5.7 L engine. 302 cu in Ford V8 = 4.9 L. Modern specs typically give litres.
What is the US Gallon?
The US liquid gallon equals exactly 3.785411784 liters and is the standard volume unit for fuel, beverages, milk, and household liquids in the United States. Defined as 231 cubic inches, the US gallon descends from the English wine gallon of 1707, which Britain replaced with the larger imperial gallon in 1824 — a divergence that left the United States with a different gallon than the rest of the English-speaking world. American gas stations price gasoline by the gallon (typical fill-up: 12–15 gallons), milk is sold in half-gallons and gallons, and many beverages come in fluid-ounce subdivisions of the gallon. The US gallon relates to the liter (1 gal ≈ 3.785 L), the quart (4 qt = 1 gal), the pint (8 pt = 1 gal), the cup (16 cups = 1 gal), and the imperial gallon (1 imp gal ≈ 1.201 US gal — about 20% larger).
- US fuel pricing and consumption
- US paint, oil and cleaning-product packaging
- US beverage containers (1-gallon jugs of milk)
US car tank ≈ 15 gallons (57 L). 1 US gallon of milk is a common grocery size (3.79 L). US paint often sold by the gallon.