Calculate gallons from cubic feet, or cubic feet from gallons, for US liquid, US dry, and Imperial gallons in one quick step.
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Cubic Feet to Gallons Formula
To convert cubic feet to gallons, multiply the volume in cubic feet by the gallons-per-cubic-foot factor for the gallon type you are using:
G = V * 7.480519
To go the other way, from gallons back to cubic feet, divide instead:
V = G / 7.480519
- G = volume in gallons
- V = volume in cubic feet (ft3)
- 7.480519 = number of US liquid gallons in one cubic foot
The factor changes with the gallon type. Use 7.480519 for US liquid gallons, 6.42851 for US dry gallons, and 6.228835 for Imperial (UK) gallons. The calculator multiplies by the factor when you convert cubic feet to gallons and divides by it when you convert gallons to cubic feet, so the same numbers run in both directions.
Gallons in One Cubic Foot by Gallon Type
The factor you pick depends on which gallon you mean. US plumbing and pool work uses the US liquid gallon, dry goods sometimes use the US dry gallon, and the UK uses the Imperial gallon.
| Gallon Type | Gallons per ft3 | ft3 per Gallon |
|---|---|---|
| US Liquid | 7.480519 | 0.133681 |
| US Dry | 6.42851 | 0.155557 |
| Imperial (UK) | 6.228835 | 0.160544 |
This table gives quick US liquid gallon values for common cubic foot amounts.
| Cubic Feet | US Liquid Gallons |
|---|---|
| 1 | 7.48 |
| 5 | 37.40 |
| 10 | 74.81 |
| 25 | 187.01 |
| 50 | 374.03 |
| 100 | 748.05 |
Example Problems
Example 1. You have a tank that holds 12 cubic feet of water and you want the volume in US liquid gallons. Multiply by 7.480519: 12 * 7.480519 = 89.77 US liquid gallons.
Example 2. A container holds 40 US liquid gallons and you want the volume in cubic feet. Divide by 7.480519: 40 / 7.480519 = 5.35 cubic feet.
Frequently Asked Questions
How many gallons are in a cubic foot? One cubic foot holds about 7.48 US liquid gallons. If you mean US dry gallons it is about 6.43, and if you mean Imperial gallons it is about 6.23.
Why are there different gallon factors? The US liquid gallon, US dry gallon, and Imperial gallon are three different units of volume. They each hold a different amount, so the number of them that fits in one cubic foot is different. Pick the gallon type that matches your source data before you convert.
Does this work for water, fuel, or any liquid? Yes. The conversion is between two units of volume, so it does not depend on what the container holds. The result is the same for water, fuel, soil, or an empty space of that size.
