Cubic Feet to Gallons Calculator
Enter a volume in cubic feet and instantly see the equivalent in US gallons, UK imperial gallons, liters, quarts and pints.
ft³
1 ft³ = 7.48052 US liquid gallons
- 1
Cubic inches in 1 ft³
12³ = 1,72812 inches per foot, cubed. - 2
Cubic inches per US gallon
231Exact US legal definition — 1 US gal = 231 in³. - 3
Gallons per ft³
1,728 ÷ 231 = 7.48052 - 4
US gallons
10 × 7.48052 = 74.8052
How does this calculator work?
Multiply cubic feet by 7.48052 to get US gallons (or by 6.22884 for UK gallons, 28.3168 for liters). The factor comes from 1 ft³ = 1728 in³ and 1 US gal = 231 in³, so 1728 ÷ 231 ≈ 7.48052.
Formula
How this is calculated
A cubic foot is the volume of a cube with sides of exactly one foot (12 inches). One US liquid gallon is defined as 231 cubic inches exactly, and since 1 ft³ = 1728 in³, the conversion factor is 1728 ÷ 231 = 7.48052 US gallons per cubic foot. This factor is fixed and exact by US definition.
The UK (imperial) gallon is slightly larger — defined as 4.54609 liters — which gives a factor of 1 ft³ ÷ 4.54609 L/gal × 28.3168 L/ft³ = 6.22884 UK gallons. Liters follow from 1 ft³ = 0.0283168 m³ = 28.3168 L. Quarts and pints are exact multiples of the US gallon (4 quarts = 1 gal; 8 pints = 1 gal).
This conversion is useful when sizing tanks, pools, aquariums, water heaters, reservoirs, and HVAC ductwork. Contractors commonly specify duct volumes in cubic feet while plumbers work in gallons — this tool bridges the two.
Frequently asked questions
One cubic foot equals exactly 7.48052 US liquid gallons, or about 6.23 UK imperial gallons. The US gallon is 231 in³ and 1 ft³ = 1728 in³, so the factor is 1728 ÷ 231 ≈ 7.48052.
No. The US liquid gallon is 3.78541 liters (231 in³), while the UK imperial gallon is 4.54609 liters — about 20% larger. Always specify which gallon you mean when communicating volumes internationally.
Multiply length × width × average depth (all in feet) to get cubic feet, then multiply by 7.48052 to get US gallons. For a round pool use π × radius² × depth × 7.48052.
Also known as
TG we-Calculate Editorial Team. (2026). Cubic Feet to Gallons Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/cubic-feet-to-gallons-calculator
TG we-Calculate Editorial Team. "Cubic Feet to Gallons Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/cubic-feet-to-gallons-calculator.
TG we-Calculate Editorial Team, "Cubic Feet to Gallons Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/cubic-feet-to-gallons-calculator
@misc{wecalculate_cubic_feet_to_gallons_calculator, title = {Cubic Feet to Gallons Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/cubic-feet-to-gallons-calculator}}, year = {2026}, note = {TG we-Calculate} }
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