Cubic Feet to Gallons
Source: NIST SP 811 Appendix B.9 and NIST Handbook 44 Appendix C for the US liquid gallon, and the Weights and Measures Act 1985 Schedule 1 for the Imperial gallon · Source verified August 14, 2026
A volume conversion tool that turns cubic feet into gallons. A cubic foot is 1,728 cubic inches and a US liquid gallon is 231 cubic inches, so the ratio is 1,728 ÷ 231, which reduces to 576/77 and does not terminate as a decimal. Any decimal form of it, including 7.48052, is rounded.
Start with a figure in cubic feet and read it back in gallons. Pick the US liquid or Imperial gallon, and the formula, the working, and the reference table all follow your choice.
Quick Answer
One cubic foot is 1,728 cubic inches, which is 1,728 ÷ 231 US liquid gallons, about 7.48052. For example, 10 cubic feet is 74.81 US gallons.
Gallon standard
1 US liquid gallon = 3.785411784 liters. The Imperial gallon is about 20% larger than the US one, so switching changes every figure below.
Answer in US liquid gallons
37.4026 gal
5 ft³ × 7.48052 = 37.4026 gal
5 cubic feet is 37.4026 US liquid gallons.
The unit relationships are exact by definition. The calculator derives this factor from those definitions, runs the calculation in double-precision floating point, and rounds the displayed result to six significant digits.
Entered: 5 ft³
Examples
1 ft³
= 7.4805 US gal
2 ft³
= 14.9610 US gal
5 ft³
= 37.4026 US gal
10 ft³
= 74.8052 US gal
How it works
Formula · US liquid: gal = ft³ × 1,728 ÷ 231 · Imperial: gal = ft³ × 28.316846592 ÷ 4.54609
A cubic foot holds a little under seven and a half US gallons. The conversion multiplies, because the cubic foot is the larger unit.
US liquid gallon
gal = ft³ × 1,728 ÷ 231
Imperial (UK) gallon
gal = ft³ × 28.316846592 ÷ 4.54609
Both factors come from definitions rather than measurement. The US liquid gallon is 231 cubic inches and the Imperial gallon is 4.54609 liters, both fixed by the standards cited below. Shorter decimals you may see elsewhere are these same values rounded.
Which gallon do you mean?
“Gallon” is not one unit. The two in common use differ by about 20%, which is far too much to ignore:
- US liquid gallon, 3.785411784 liters. The default here, and what United States fuel, beverage, and recipe figures mean.
- Imperial gallon, 4.54609 liters. About 20% larger. Used in the United Kingdom and parts of the Commonwealth.
There is also a US dry gallon, a separate unit for dry goods that this page does not convert. If a figure came from a fuel pump, a drinks label, or a recipe, it is a liquid gallon.
Cubic Feet to Gallons reference table
Converted columns are rounded for display, so they are equivalents rather than exact statements. Both gallon standards are shown side by side.
| Cubic Feet | US liquid gal | Imperial gal | Note |
|---|---|---|---|
| 1 ft³ | 7.4805 | 6.2288 | One cubic foot |
| 2 ft³ | 14.9610 | 12.4577 | |
| 5 ft³ | 37.4026 | 31.1442 | |
| 10 ft³ | 74.8052 | 62.2884 | |
| 25 ft³ | 187.0130 | 155.7209 | |
| 50 ft³ | 374.0260 | 311.4418 | |
| 100 ft³ | 748.0519 | 622.8835 |
Common mistakes
- Using the wrong gallon. One cubic foot is 7.48052 US gallons but 6.22884 Imperial gallons.
- Rounding 7.48 too early. The true ratio is 1,728 ÷ 231, which repeats and never terminates, so rounding it early shifts large volumes.
- Converting linear feet instead of cubic feet. A cubic foot is 12 × 12 × 12 = 1,728 cubic inches, not 12.
Sources
- NIST Special Publication 811, Appendix B.9, which gives the inch as exactly 2.54 cm. Cubing that gives the cubic inch as exactly 16.387064 cm³.
- NIST Handbook 44, Appendix C, which defines the US liquid gallon as 231 cubic inches. With the inch above that fixes the US gallon at exactly 3.785411784 liters.
- Weights and Measures Act 1985, Schedule 1, which defines the Imperial gallon as 4.54609 cubic decimetres, that is 4.54609 liters.
These relationships are exact as definitions. The calculator derives its factor from them, computes in double-precision floating point, and rounds what it displays.
Related converters
- Cubic inches to gallons for the smaller cubic unit the gallon is defined from.
- Gallons to liters to take the gallon answer into metric.
- Volume calculator to work out the cubic feet of a shape first.
- Volume converter for cups, pints, quarts, and more.
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