Enter nonnegative length, width, and height in feet.
Because 1 ft = exactly 0.3048 m, 1 ft³ = 0.3048³ = 0.028316846592 m³ = 28.316846592 L. Because 1 ft³ is 1,728 in³ and one U.S. liquid gallon is 231 in³, 1 ft³ = 1,728 ÷ 231 = 7.480519480519… US gal.
A 4 ft × 4 ft × 4 ft box is 64 ft³, 1.812278181888 m³, about 478.753247 US gal, and 1,812.278181888 L. The form rejects dimensions whose products or converted equivalents are invalid numeric results.
Turn the result into other units with the cubic feet to U.S. gallons converter or the cubic feet to cubic meters converter, or compute a metric volume directly with the cubic meter calculator.
Measure usable interior dimensions
For a rectangular container, enter interior length, width, and height in feet rather than exterior dimensions or dimensions copied in inches. Keep an irregular object’s bounding-box estimate labeled as such. The converted gallons describe geometric volume, not how much liquid the container is rated to hold.
Make a dimension record before converting capacity
Use a single consistent record for a rectangular space:
| Field | What to measure | What to avoid mixing |
|---|---|---|
| Length | Interior length in feet | An exterior dimension from another drawing |
| Width | Interior width in feet | A number still expressed in inches |
| Height | The height of the modeled space | A separate nominal capacity label |
The converted volume is geometric. Keep any deduction for fittings or fill reserve as a separate usable-capacity assumption rather than implying it is already included.
Sources
- NIST, Guide for the Use of the International System of Units (SP 811) — SI units and accepted conversion guidance.
- NIST, Handbook 44, Appendix C — U.S. customary volume and length relationships used for dimensional arithmetic.