Cubic Feet to Gallons Converter
Enter a volume in cubic feet to get the equivalent in US liquid gallons or UK imperial gallons - or go the other way and convert gallons back to cubic feet. The result updates instantly, and the Steps panel shows the exact arithmetic so you can verify every digit.
Cubic feet and gallons: understanding the units
A cubic foot (ft3) is the volume of a cube with sides exactly 1 foot (30.48 cm) long. It is commonly used in the United States and United Kingdom to measure volumes of air, soil, concrete, water tanks and shipping containers. A gallon, on the other hand, is a unit of liquid volume. There are two different gallons in everyday use: the US liquid gallon (3.785411784 litres, defined exactly) and the UK imperial gallon (4.54609 litres, also defined exactly). The US gallon is used in the United States for measuring fuel, water and most other liquids. The UK gallon is used in the United Kingdom, Canada and several Commonwealth countries. Because the two gallons differ by about 20%, it is important to specify which one you need before converting from cubic feet.
Conversion formulas
The relationship between cubic feet and gallons follows directly from the definition of each unit. To convert cubic feet to US liquid gallons, multiply by 7.4805195 (the number of US gallons in one cubic foot). To convert to UK imperial gallons, multiply by 6.2288355. Going the other way, divide by the same factor - or equivalently, multiply cubic feet by 0.1336806 (US) or 0.1605437 (UK). Worked example: a 10 ft3 water heater tank holds 10 x 7.4805 = 74.805 US gallons, or 10 x 6.2288 = 62.288 UK gallons. Another example: 50 US gallons = 50 x 0.1336806 = 6.684 ft3.
When does this conversion matter?
Converting between cubic feet and gallons is important in several practical situations. Homeowners calculate hot-water heater or water-softener capacity, which is often sold in gallons, against the cubic-foot space available in a utility closet. Irrigation engineers size retention ponds and tanks whose volumes are published in cubic feet but billed in gallons. Aquarium keepers convert display tank dimensions (measured in feet) to gallons for stocking-density rules. Pool contractors estimate the volume of a rectangular pool by multiplying length x width x depth in feet and then converting to gallons to determine pump size and chemical dosages. Utility bills in parts of the United States report water usage in hundred cubic feet (HCF or CCF); 1 CCF = 748.05 US gallons.
US gallon vs. UK gallon: which should you use?
If you are in the United States or converting values from American sources, use the US liquid gallon (3.785 L). All American water bills, fuel prices and appliance ratings use this definition. If you are in the United Kingdom, Canada, Australia or another country that uses the imperial system, use the UK imperial gallon (4.546 L). Do not mix the two: quoting a 50-gallon tank in UK gallons when the manufacturer means US gallons overstates the volume by about 20%, which can lead to under-ordering of chemicals or over-sizing pumps. When in doubt, check the country of origin for the specification.
Cubic feet to gallons: quick-reference table
| Cubic feet (ft³) | US gallons | UK gallons |
|---|---|---|
| 0.5 | 3.7403 | 3.1144 |
| 1 | 7.4805 | 6.2288 |
| 2 | 14.961 | 12.4577 |
| 3 | 22.4416 | 18.6865 |
| 4 | 29.922 | 24.9153 |
| 5 | 37.4026 | 31.1442 |
| 6 | 44.8831 | 37.373 |
| 7 | 52.3637 | 43.6018 |
| 8 | 59.8442 | 49.8307 |
| 9 | 67.3247 | 56.0595 |
| 10 | 74.8052 | 62.2884 |
| 12 | 89.7662 | 74.746 |
| 15 | 112.2078 | 93.4328 |
| 20 | 149.6104 | 124.577 |
| 25 | 187.013 | 155.721 |
| 50 | 374.026 | 311.442 |
| 100 | 748.052 | 622.884 |
Values rounded to 4 decimal places. US gallon = 3.785411784 L, UK gallon = 4.54609 L.
Frequently asked questions
How many gallons are in a cubic foot?
One cubic foot contains 7.4805195 US liquid gallons or 6.2288355 UK imperial gallons. The US gallon is defined as exactly 3.785411784 litres and the UK gallon as exactly 4.54609 litres. Because one cubic foot is 28.316846592 litres, dividing by 3.785411784 gives 7.4805, and dividing by 4.54609 gives 6.2288.
How do I convert cubic feet to gallons by hand?
Multiply the number of cubic feet by 7.48 for a quick US-gallon approximation, or by 6.23 for a UK-gallon approximation. For more precision use 7.4805195 (US) or 6.2288355 (UK). For example, 5 ft3 x 7.4805 = 37.40 US gallons.
What is the difference between a US gallon and a UK gallon?
The US liquid gallon is exactly 3.785411784 litres. The UK imperial gallon is exactly 4.54609 litres. That makes the UK gallon about 20% larger. In cubic-foot terms, 1 ft3 equals 7.48 US gallons but only 6.23 UK gallons. Always confirm which standard applies when using a manufacturer specification from an international source.
How do I convert gallons back to cubic feet?
Divide US gallons by 7.4805195 (or multiply by 0.1336806). Divide UK gallons by 6.2288355 (or multiply by 0.1605437). For example, 100 US gallons / 7.4805 = 13.37 ft3. You can also switch this calculator to "Gallons to cubic feet" mode and type the gallons directly.
How many gallons of water are in a 1,000 cubic foot pool?
1,000 ft3 x 7.4805 = 7,480.5 US gallons, or 1,000 x 6.2288 = 6,228.8 UK gallons. A typical residential in-ground swimming pool holds about 25,000 US gallons, which is roughly 3,341 ft3. Irregular-shaped pools require dividing the shape into rectangular sections, calculating each volume, and then summing them before converting.
Why do US utility bills sometimes use "CCF" instead of gallons?
CCF stands for hundred cubic feet (100 ft3). It is a traditional billing unit used by many US water utilities because flow meters measure volume in cubic feet. 1 CCF = 100 ft3 = 748.05 US gallons. To convert your water bill from CCF to gallons, multiply the CCF figure by 748.