Gallons to Cubic Feet
Convert gallons (gal) to cubic feet (ft³). Both measure capacity and volume, and the conversion comes up in cooking, chemistry, fuel work.
The Formula
``
cubic feet = gallons × 0.133680555556
gallons = cubic feet × 7.48051948052
`
One gallon is 0.133681 cubic feet, and one cubic feet is 7.4805 gallons.
Conversion Table
| 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 |
The Other Direction
| 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 |
What Each Unit Is
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.
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.
A Sense of Scale
A US milk jug is 1 gallon- A car tank is 12–16 gallons
- US fuel economy is miles per gallon
- A domestic fridge is 18–25 ft³
- Airflow is rated in cubic feet per minute
Doing It in Your Head
Multiply by 2, then divide by 15. 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 1.3368 ft³ 1.3333 ft³ 13.3681 ft³ 13.3333 ft³
Precision
The factor 0.133680555556 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 gallonToCubicFoot = (value) => value * 0.133680555556;
``
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 gal with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 gal becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0.1 | 13.7 | 25.1948% |
| 2 | 0.13 | 17.81 | 2.7532% |
| 3 | 0.134 | 18.358 | 0.2390% |
| 4 | 0.1337 | 18.3169 | 0.0145% |
The right number of significant figures is set by your input, not by the converter. If you measured gallons to three significant figures, the answer in cubic feet is only good to three — writing more digits claims precision the measurement never had.