About the Gallons to Cubic Feet Converter
This gallons to cubic feet converter changes a volume in US or UK (imperial) gallons into cubic feet, and works in reverse when you start from cubic feet. It also shows the same volume in liters and cubic meters, so you can compare tank labels, pool volumes and appliance specs in whichever unit you need.
Typical uses include sizing a water heater or aquarium, working out how much space a fuel or rain tank takes up, converting pool and pond volumes for chemical dosing charts, and checking freezer or cargo capacities listed in cubic feet.
Be sure to pick the right gallon. A US liquid gallon is 231 cubic inches (about 3.785 L) while a UK imperial gallon is 4.54609 L, about 20% larger, so one cubic foot holds about 7.48 US gallons but only about 6.23 imperial gallons.
With the default inputs, the cubic feet is 13.3681 ft³. Change any value above to recalculate instantly.
How to use the gallons to cubic feet converter
- 1Enter the volume.
- 2Choose whether it is in US gallons, UK gallons or cubic feet.
- 3Read cubic feet as the main result, with gallons, liters and cubic meters below.
- 4Use the chart for common tank and drum sizes.
Formula and method
A US liquid gallon is defined as exactly 231 cubic inches and a cubic foot is 12 × 12 × 12 = 1,728 cubic inches, so one cubic foot holds 1728 ÷ 231 ≈ 7.480519 US gallons. Dividing US gallons by 7.480519 gives cubic feet.
The UK imperial gallon is defined as exactly 4.54609 liters, and one cubic foot is 0.3048³ m³ = 28.316846592 liters, so a cubic foot holds about 6.228835 imperial gallons. The converter works through liters internally, which keeps every direction exact.
- 231
- Cubic inches per US liquid gallon (exact)
- 1728
- Cubic inches per cubic foot
- 28.316846592
- Liters per cubic foot (exact)
- 4.54609
- Liters per UK gallon (exact)
Worked examples
100 US gallon tank
100 × 231 = 23,100 cubic inches; 23,100 ÷ 1,728 = 13.368 ft³. That is 378.54 liters.
20 cubic foot freezer in gallons
20 × 7.480519 = 149.61 US gallons, or 20 × 6.228835 = 124.58 UK gallons.
50 UK gallon water butt
50 × 4.54609 = 227.30 L; 227.30 ÷ 28.3168 = 8.027 ft³, which is about 60.05 US gallons.
Frequently asked questions
How many gallons are in a cubic foot?+
One cubic foot holds about 7.4805 US liquid gallons, or about 6.2288 UK imperial gallons.
How do I convert gallons to cubic feet?+
Divide US gallons by 7.4805 (or multiply by 0.13368). For imperial gallons, divide by 6.2288 (or multiply by 0.16054).
How many cubic feet is a 55-gallon drum?+
A 55 US gallon drum holds 55 ÷ 7.4805 ≈ 7.35 cubic feet of liquid. The outside of the drum takes up a little more space.
Why are US and UK gallons different?+
The US gallon descends from the old English wine gallon of 231 cubic inches, while the UK redefined its gallon in 1824 based on 10 pounds of water. The UK gallon is about 20% larger.
How do I find a pool volume in gallons from cubic feet?+
Multiply length × width × average depth in feet to get cubic feet, then multiply by 7.48 to get US gallons. A 30 × 15 × 5 ft pool is 2,250 ft³ ≈ 16,831 gallons.