SettingsSettings for this calculationUS
The volume value to convert.
Useful for tank capacity, pond volume, or rainwater storage sizing.
The unit your starting value is in.
The result shows the equivalent in the other unit.
Converted volume
13.37 ft³
Exact: a US gallon is defined as 231 cubic inches and a cubic foot is 1,728, so one cubic foot is 1728 ÷ 231 = 7.4805 US gallons. An imperial gallon is about a fifth larger — check which one a tank or pump rating means.
- US gallons entered
- 100 gal
- Litres
- 378.54 L
They open the calculator with your figures already in it
Gallons to Cubic Feet Calculator: 13.37 ft³ — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- NIST Handbook 44, Appendix C — 1 US liquid gallon = 231 cubic inches (exact)
- 1 cubic foot = 1,728 cubic inches, so 1 ft³ = 1728 ÷ 231 = 7.4805 US gallons exactly
Inputs used
- Volume
- 100
- Converting From
- Gallons
Intermediate steps
- US gallons entered
- 100 gal
- Litres
- 378.54 L
Confidence note: Exact: a US gallon is defined as 231 cubic inches and a cubic foot is 1,728, so one cubic foot is 1728 ÷ 231 = 7.4805 US gallons. An imperial gallon is about a fifth larger — check which one a tank or pump rating means.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-16 · v1.1.0
Regulatory standards & verification citations2
- NIST Handbook 44, Appendix C — 1 US liquid gallon = 231 cubic inches (exact)
- 1 cubic foot = 1,728 cubic inches, so 1 ft³ = 1728 ÷ 231 = 7.4805 US gallons exactly
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.