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Convert cubic feet to gallons

Convert cubic feet to gallons instantly. 1 ft³ = 7.480519 gal. Formula, worked examples and a quick reference table.

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ft³
gal

One cubic foot equals 7.480519 us gallons. To convert any number of cubic feet to us gallons, multiply by 7.48051948.

The converter above works in both directions and updates as you type. Below you will find the formula, a worked example and a reference table of common values.

Volume is the category where the US and imperial systems diverge most damagingly. Gallons, quarts, pints and fluid ounces all exist in two sizes that differ by up to 20%, and nothing in the name warns you which one a figure uses. Recipes, fuel economy figures and container capacities all cross borders regularly, so it is worth checking which system a source is using before converting rather than after.

cubic feet to gallons formula

us gallon = cubic foot × 7.48051948

To go the other way, use cubic foot = us gallon ÷ 7.48051948.

About these units

A cubic foot is 28.3 litres. It persists in US appliance capacities, shipping volumes and natural gas measurement.

A US gallon is 231 cubic inches, about 3.785 litres. It is noticeably smaller than the imperial gallon, which is a frequent source of fuel-economy confusion.

Cubic Foot is also written cubic feet, cu ft, ft3 and ft^3. US Gallon is also written gallons, gals and us gal.

Sources

  1. National Bureau of Standards, "Refinement of Values for the Yard and the Pound", Federal Register, 1 July 1959 — the international yard as exactly 0.9144 m and the avoirdupois pound as exactly 0.45359237 kg.
  2. NIST Special Publication 811, Guide for the Use of the International System of Units (SI), 2008 edition — conversion factors for units outside the SI.

cubic feet to gallons conversion table

Cubic Foot US Gallon
1 ft³ 7.4805 gal
2 ft³ 14.961 gal
3 ft³ 22.4416 gal
5 ft³ 37.4026 gal
10 ft³ 74.8052 gal
20 ft³ 149.6104 gal
25 ft³ 187.013 gal
50 ft³ 374.026 gal
100 ft³ 748.0519 gal
250 ft³ 1,870.1299 gal
500 ft³ 3,740.2597 gal
1,000 ft³ 7,480.5195 gal

Frequently asked questions

How many us gallons are in a cubic foot? +

There are 7.480519 us gallons in one cubic foot.

What is 10 ft³ in gal? +

10 ft³ equals 74.8052 gal. Multiply 10 by 7.48051948.

How do I convert us gallon back to cubic foot? +

Use cubic foot = us gallon ÷ 7.48051948. The converter above handles both directions, or see our dedicated gallons to cubic feet page.

How accurate is this cubic foot to us gallon conversion? +

The factor used is 7.4805194805, carried at full double precision. Where a unit has an exact legal definition the factor is exact rather than approximate. Rounding is applied only to the displayed result, so the answer is never a calculation done on an already-rounded number.

Is there a quick way to estimate ft³ to gal in my head? +

Multiply by 15 and divide by 2. That approximates the true factor of 7.480519 to within 0.2604%, which is close enough for a mental estimate.