Convert Cubic Feet to Gallons Instantly
Use this Cubic Feet to Gallons converter to change cubic feet (ft³) into U.S. liquid gallons instantly. Enter any whole or decimal volume, reverse gallons back to cubic feet, compare Imperial gallons, or use the multi-unit converter for cubic yards, liters and cubic meters.
Use the main ft³-to-gallon calculator, reverse gallons to cubic feet, compare Imperial gallons, or convert one volume across multiple units.
Enter cubic feet to calculate U.S. liquid gallons and related volume units.
Decimals are supported, such as 0.5 or 12.75 ft³.
Reverse the calculation by converting U.S. liquid gallons into cubic feet.
100 U.S. gallons ≈ 13.3681 ft³.
Convert cubic feet to UK/Imperial gallons without mixing the Imperial gallon with the smaller U.S. liquid gallon.
1 ft³ ≈ 6.228835459 Imperial gallons.
Enter one volume and convert it into cubic feet, U.S. gallons, Imperial gallons, liters, cubic meters and cubic yards.
To convert cubic feet to gallons, first decide which gallon standard you need. In U.S. construction, plumbing, storage and general capacity calculations, an unqualified gallon usually refers to the U.S. liquid gallon. One cubic foot contains approximately 7.4805194805 U.S. liquid gallons, so the calculation is a direct multiplication.
Example: 12 ft³ × 7.4805194805 = 89.766233766 gallons.
Example: 100 gal ÷ 7.4805194805 ≈ 13.368055556 ft³.
The factor comes from exact U.S. customary relationships: one cubic foot contains 1,728 cubic inches, while one U.S. liquid gallon contains 231 cubic inches. Dividing 1,728 by 231 gives 7.4805194805 gallons per cubic foot.
NIST conversion tables list the cubic foot as approximately 2.831685 × 10−2 cubic meter and provide the customary/SI relationships used to derive precise volume conversions. See the NIST Guide to the SI, Appendix B.8 for authoritative conversion factors.
A U.S. liquid gallon equals 3.785411784 liters, while an Imperial gallon equals 4.54609 liters. Because the Imperial gallon is larger, the same cubic-foot volume produces fewer Imperial gallons than U.S. gallons.
The chart below converts common cubic-foot values to U.S. liquid gallons, Imperial gallons and liters. On mobile devices, the table stays inside the responsive wrapper so users can scroll sideways without breaking the page width.
| Cubic Feet | U.S. Gallons | Imperial Gallons | Liters |
|---|---|---|---|
| 0.1 ft³ | 0.748052 gal | 0.622884 Imp gal | 2.831685 L |
| 0.25 ft³ | 1.870130 gal | 1.557209 Imp gal | 7.079212 L |
| 0.5 ft³ | 3.740260 gal | 3.114418 Imp gal | 14.158423 L |
| 1 ft³ | 7.480519 gal | 6.228835 Imp gal | 28.316847 L |
| 2 ft³ | 14.961039 gal | 12.457671 Imp gal | 56.633693 L |
| 3 ft³ | 22.441558 gal | 18.686506 Imp gal | 84.950540 L |
| 5 ft³ | 37.402597 gal | 31.144177 Imp gal | 141.584233 L |
| 10 ft³ | 74.805195 gal | 62.288355 Imp gal | 283.168466 L |
| 20 ft³ | 149.610390 gal | 124.576709 Imp gal | 566.336932 L |
| 25 ft³ | 187.012987 gal | 155.720886 Imp gal | 707.921165 L |
| 50 ft³ | 374.025974 gal | 311.441773 Imp gal | 1,415.842330 L |
| 75 ft³ | 561.038961 gal | 467.162659 Imp gal | 2,123.763494 L |
| 100 ft³ | 748.051948 gal | 622.883546 Imp gal | 2,831.684659 L |
| 250 ft³ | 1,870.129870 gal | 1,557.208865 Imp gal | 7,079.211648 L |
| 500 ft³ | 3,740.259740 gal | 3,114.417730 Imp gal | 14,158.423296 L |
| 1000 ft³ | 7,480.519481 gal | 6,228.835459 Imp gal | 28,316.846592 L |
0.5 × 7.48051948 = 3.74026 gal.
2 × 7.48051948 = 14.96104 gal.
10 × 7.48051948 = 74.80519 gal.
50 × 7.48051948 = 374.02597 gal.
The same multiplier works for decimal values. For example, 3.75 ft³ equals approximately 28.05195 gallons. Keep extra digits through the calculation when tank capacity, engineering or estimating precision matters, and round only the final displayed result.
The relationship is easy to verify through cubic inches. A foot is 12 inches, so a cube measuring one foot on every side contains 12 × 12 × 12 = 1,728 cubic inches. A U.S. liquid gallon is defined as 231 cubic inches. Therefore, 1,728 ÷ 231 = 7.4805194805 U.S. gallons.
A one-foot cube has a fixed geometric volume. The same space can be expressed as cubic feet, gallons, liters or cubic yards.
Tank and reservoir dimensions are often measured in feet while capacity is quoted in gallons. If you know the internal volume in cubic feet, multiplying by 7.4805194805 gives the theoretical U.S. gallon capacity. This is especially useful for rectangular tanks, cisterns, sumps, aquariums and storage basins.
For a rectangular tank measured in feet, calculate internal length × width × liquid depth to get cubic feet. A tank with an internal liquid space of 4 ft × 3 ft × 2 ft contains 24 ft³. Multiplying 24 by 7.4805194805 gives about 179.5325 U.S. gallons.
Small pools, ponds and water features are often planned with dimensions in feet but pumps, filters, chemical treatments and refill quantities are specified in gallons. Converting the calculated cubic-foot volume into gallons creates a common basis for equipment sizing and maintenance planning.
For irregular shapes, a simple length × width × depth estimate may overstate or understate the true volume. Use an appropriate geometric method or an average-depth estimate, then convert the resulting cubic feet to gallons. The unit conversion itself is exact for the units; the uncertainty usually comes from the shape and measurement assumptions.
1 cubic foot ≈ 7.4805194805 U.S. gal.
1 U.S. liquid gallon = 3.785411784 liters.
1 cubic foot ≈ 6.228835459 Imperial gal.
1 Imperial gallon = 4.54609 liters.
Always confirm which gallon a source uses before converting. A 100-gallon U.S. tank and a 100-gallon Imperial tank do not have the same volume. This page uses U.S. liquid gallons for the main Cubic Feet to Gallons calculator and provides the separate Imperial panel for UK-style gallon conversions.
For the reverse conversion, divide U.S. liquid gallons by 7.4805194805. Equivalently, multiply gallons by approximately 0.1336805556 cubic foot per gallon.
Example: 250 gal × 0.1336805556 ≈ 33.4201389 ft³.
The reverse calculator above performs this automatically and also reports liters and cubic yards so you can compare the same capacity across several common volume systems.
A cubic foot is the volume of a cube one foot long, one foot wide and one foot high. A cubic yard is much larger: one cubic yard contains exactly 27 cubic feet. Therefore one cubic yard contains about 201.974 U.S. liquid gallons. This relationship is useful for construction and landscaping projects where bulk material volumes are quoted in cubic yards but liquid volumes or tank capacities appear in gallons.
If your starting measurement is in cubic yards, use the related Cubic Yards to Gallons converter. If you need the intermediate unit, see Cubic Feet to Cubic Yards or Cubic Yards to Cubic Feet.
One cubic foot equals 0.028316846592 cubic meter, or 28.316846592 liters. Because one U.S. gallon equals 3.785411784 liters, dividing 28.316846592 by 3.785411784 produces approximately 7.4805194805 gallons.
Metric conversion can be useful when equipment documentation uses liters or cubic meters. You can also use related pages such as Liters to Gallons, Gallons to Liters and Cubic Meters to Gallons.
Continue with related converters including Gallons to Cubic Feet, Cubic Yards to Gallons, Gallons to Cubic Yards, Liters to Cubic Feet, Cubic Feet to Liters and the Volume Converter. These internal links let users switch between liquid-capacity units and cubic dimensions without manually chaining multiple formulas.
For exact and standardized unit-conversion references, consult NIST SP 811 Appendix B.8 and the broader NIST Unit Conversion resources. These references are useful when conversion factors are needed for technical, scientific, engineering or trade applications.
Quick answers about ft³-to-gallon formulas, common capacities, Imperial gallons, liters and reverse conversions.