Cubic Feet to Gallons
Convert cubic feet (ft³) to gallons (gal). Both measure capacity and volume, and the conversion comes up in cooking, chemistry, fuel work.
The Formula
``
gallons = cubic feet × 7.48051948052
cubic feet = gallons × 0.133680555556
`
One cubic feet is 7.4805 gallons, and one gallon is 0.133681 cubic feet.
Conversion Table
| Cubic Feet | Gallons |
|---|---|
| 1 ft³ | 7.4805 gal |
| 2 ft³ | 14.961 gal |
| 5 ft³ | 37.4026 gal |
| 10 ft³ | 74.8052 gal |
| 25 ft³ | 187.013 gal |
| 50 ft³ | 374.026 gal |
| 100 ft³ | 748.0519 gal |
| 500 ft³ | 3,740.26 gal |
| 1,000 ft³ | 7,480.52 gal |
The Other Direction
| Gallons | Cubic Feet |
|---|---|
| 1 gal | 0.133681 ft³ |
| 2 gal | 0.267361 ft³ |
| 5 gal | 0.668403 ft³ |
| 10 gal | 1.3368 ft³ |
| 25 gal | 3.342 ft³ |
| 50 gal | 6.684 ft³ |
| 100 gal | 13.3681 ft³ |
| 500 gal | 66.8403 ft³ |
| 1,000 gal | 133.6806 ft³ |
What Each Unit Is
Cubic Feet (ft³) — the volume of a cube one foot on each side, or 28.3168 litres. The imperial volume unit for freight, appliances and ventilation.
Gallons (gal) — the US liquid gallon: exactly 3.785411784 litres. The English wine gallon of 231 cubic inches, kept by the US after Britain moved on in 1824.
A Sense of Scale
A domestic fridge is 18–25 ft³- Airflow is rated in cubic feet per minute
- A US milk jug is 1 gallon
- A car tank is 12–16 gallons
- US fuel economy is miles per gallon
Doing It in Your Head
Multiply by 15, then divide by 2. That is off by 0.26% — close enough to judge a
distance, a weight or a price, and not close enough to sign off on a drawing.
Exact Mental shortcut 74.8052 gal 75 gal 748.0519 gal 750 gal
Precision
The factor 7.48051948052 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- The UK imperial gallon is 4.546 litres — 20% larger. A "gallon" without a country attached is ambiguous, and US MPG figures look worse when read as imperial.
In Code
`javascript
const cubicFootToGallon = (value) => value * 7.48051948052;
``
Where This Conversion Comes Up
- Cooking
- Chemistry
- Fuel
- Beverages
- Medicine
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 ft³ with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 ft³ becomes | Error |
|---|---|---|---|
| 0 | 7 | 959 | 6.4236% |
| 1 | 7.5 | 1,027.5 | 0.2604% |
| 2 | 7.48 | 1,024.76 | 0.0069% |
| 3 | 7.481 | 1,024.9 | 0.0064% |
| 4 | 7.4805 | 1,024.83 | 0.0003% |
The right number of significant figures is set by your input, not by the converter. If you measured cubic feet to three significant figures, the answer in gallons is only good to three — writing more digits claims precision the measurement never had.