cubic feet to gallons calculator
Convert cubic feet to US gallons and liters. Formula, worked example, and a reference table for tank, pool, and pump sizing.
Tank and pool dimensions are easy to measure in feet, but capacity, water bills, and chemical dosing all run in gallons. This calculator converts a cubic-foot volume into gallons and liters, so you can go from a taped measurement straight to a number you can act on.
How this calculator works
One cubic foot holds 7.48052 US gallons — the standard water-volume conversion factor.
Formula: Gallons = Cubic feet × 7.48052. Liters = Cubic feet × 28.3168.
Worked example
Enter 100 cubic feet, the calculator’s default:
- Gallons: 100 × 7.48052 ≈ 748.1 gal
- Liters: 100 × 28.3168 ≈ 2,831.7 L
That’s close to the volume of a mid-size residential water cistern.
Reference
| Cubic feet | Gallons | Liters |
|---|---|---|
| 25 cu ft | 187.0 gal | ≈707.9 L |
| 100 cu ft | 748.1 gal | ≈2,831.7 L |
| 250 cu ft | 1,870.1 gal | ≈7,079.2 L |
| 500 cu ft | 3,740.3 gal | ≈14,158.4 L |
How this conversion is used
Once you know a tank, pond, or pool’s volume in cubic feet from measuring its dimensions, converting to gallons lets you compare it against a manufacturer’s rated capacity, size a pump, or calculate chemical dosing (most treatment products are dosed per gallon). To go the other direction — starting from a gallon rating and finding the cubic feet — use the Gallons to Cubic Feet Calculator, or size a swimming pool’s gallons directly with the Pool Gallons Calculator.
Frequently asked questions
How many gallons are in a cubic foot?
One cubic foot holds 7.48052 US gallons. This is one of the most-used constants in plumbing and pool math because water volume is almost always reported in gallons even when the container is measured in feet.
Why measure a tank in cubic feet first?
Cubic feet come straight from length × width × height (or radius and height for a cylinder), all of which are easy to measure with a tape measure. Converting to gallons afterward avoids doing gallon math with awkward mid-calculation unit conversions.
Does this work for pools?
Yes — find the pool's volume in cubic feet (length × width × average depth for rectangular pools), then multiply by 7.48052 to get gallons for chemical dosing. Irregular shapes like ovals need an adjusted area formula first.
Is the result different for other liquids?
No — this is a pure volume conversion (cubic feet to gallons is the same ratio regardless of what fills the space). Weight-based conversions would differ by liquid, but this calculator only converts volume.
How do I go from gallons back to cubic feet?
Multiply gallons by 0.133681, or use our Gallons to Cubic Feet Calculator directly.
Estimates only. Verify quantities with your supplier before purchasing.