1. How to convert cubic feet to gallons
The conversion is a single multiplication: gal = ft³ × 7.48051948052. Both units are defined
against the same base — the litre (L) — so the factor is fixed and the result
is exact to the precision shown.
Worked at the two values people ask for most: 1 ft³ = 7.4805195 gal and
5 ft³ = 37.402597 gal. Going the other way, ft³ = gal × 0.133680555556, so
1 gal = 0.13368056 ft³.
Results are given to eight significant figures. That is more precision than most jobs need — for a rough figure, treat 1 ft³ as about 7.4805195 gal and adjust — but rounding early and multiplying afterwards is how a small error becomes a visible one, so the full figure is what the converter carries.
2. Cubic feet to Gallons conversion table
| Cubic feet (ft³) | Gallons (US) (gal) |
|---|---|
| 1 ft³ | 7.4805195 gal |
| 2 ft³ | 14.961039 gal |
| 3 ft³ | 22.441558 gal |
| 5 ft³ | 37.402597 gal |
| 10 ft³ | 74.805195 gal |
| 15 ft³ | 112.20779 gal |
| 20 ft³ | 149.61039 gal |
| 50 ft³ | 374.02597 gal |
| 100 ft³ | 748.05195 gal |
Every row is the same factor applied — nothing in the table is a special case, and any value in between behaves the same way. Type your own figure into the converter above and the Formula tile shows the arithmetic being used, so the result is checkable rather than taken on trust.
3. What the two units are
- Cubic feet (ft³). One ft³ is 28.316847 L.
- Gallons (US) (gal). One gal is 3.7854118 L.
Both are converted through the litre (L): the value is multiplied by its own unit's factor to reach the base, then divided by the target unit's factor to leave it. No direct cubic feet to gallons factor has to exist or be kept correct, which is also why the converter can show the same value in all 14 volume & capacity units at once.
US and imperial capacity units share names but not sizes. A US gallon is exactly 3.785411784 L and an imperial gallon exactly 4.54609 L — 20% larger — while the imperial fluid ounce is the smaller ounce, because an imperial gallon is 160 fluid ounces where a US gallon is 128. Every unit here is labelled US or imperial for that reason.
If the pair you actually want is not this one, the full unit converter runs every 14 volume & capacity units off the same factor table, along with 11 other categories of measurement.
4. Cubic feet to Gallons FAQs
How do I convert cubic feet to gallons?
Multiply by 7.48051948052. 1 ft³ = 7.4805195 gal, and 5 ft³ = 37.402597 gal. The factor is exact to the precision shown, so the only rounding is the one you choose to do at the end.
How many gallons is 1 ft³?
1 ft³ = 7.4805195 gal. The full formula is gal = ft³ × 7.48051948052, and 1 gal = 0.13368056 ft³ going the other way.
What is 5 ft³ in gal?
5 ft³ = 37.402597 gal. The table above works the same factor through 9 values, and the converter takes any figure you type — including decimals.
How do I convert gal to ft³?
ft³ = gal × 0.133680555556, so 1 gal = 0.13368056 ft³. Use the Swap button in the converter to reverse the direction without retyping the value.
US or imperial?
Both are in the converter and every unit is labelled. A US gallon is exactly 3.785411784 L and an imperial gallon exactly 4.54609 L, a 20% difference; the imperial fluid ounce is the smaller of the two ounces, because an imperial gallon holds 160 of them against a US gallon’s 128.
Is anything I type sent to a server?
No. The factor table ships with the page and every conversion runs in your browser. Nothing is uploaded, logged or written to storage, and the converter keeps working offline once the page has loaded.