A cubic foot and a US gallon both have exact definitions in cubic inches, making this a precise volume conversion.
How it works
A cubic foot is exactly 1,728 cubic inches; a gallon is exactly 231 cubic inches. Dividing gives the exact 7.4805 gallons-per-cubic-foot ratio used to convert in either direction.
What this does not include
This does not include computing cubic feet from dimensions — for that, use this site’s cubic feet calculator instead. This tool converts an already-known cubic-feet figure to gallons.
How to use this calculator
- Enter a value in either cubic feet or gallons — the other field fills in automatically.
Frequently asked questions
Where is this conversion commonly needed?
Water tank and pool capacity, HVAC and plumbing sizing, and comparing volume specs given in different units.
Why isn’t the ratio a round number?
Because a cubic foot (1,728 cubic inches) and a gallon (231 cubic inches) were defined independently, not designed to divide evenly into each other.
Is a US gallon the same as an imperial gallon?
No — an imperial gallon is larger, so this conversion applies specifically to the US gallon definition.
