Cubic Feet to Gallons Conversion (ft³ to gal)
Official NIST legal conversion rate, common reference values table, and practical application guide.
Exact Conversion Factor (NIST SP 811)
1 Cubic Foot (ft³) = 7.480519 US Liquid Gallons (exact NIST definition)
Practical Context & Real-World Use
This conversion is universally used for sizing residential water heaters, aquarium stocking levels, rainwater harvesting cisterns, and hot tubs.
Quick Reference Table (ft³ to gal)
| ft³ | gal | Conversion Math |
|---|---|---|
| 1 ft³ | 7.48 gal | 1 × 7.4805 = 7.48 |
| 2 ft³ | 14.96 gal | 2 × 7.4805 = 14.96 |
| 5 ft³ | 37.4 gal | 5 × 7.4805 = 37.4 |
| 10 ft³ | 74.81 gal | 10 × 7.4805 = 74.81 |
| 25 ft³ | 187.01 gal | 25 × 7.4805 = 187.01 |
| 50 ft³ | 374.03 gal | 50 × 7.4805 = 374.03 |
| 100 ft³ | 748.05 gal | 100 × 7.4805 = 748.05 |
| 500 ft³ | 3740.26 gal | 500 × 7.4805 = 3740.26 |
| 1000 ft³ | 7480.52 gal | 1000 × 7.4805 = 7480.52 |
Frequently Asked Questions
How many gallons are in a cubic foot?▼
There are exactly 7.480519 US liquid gallons in one cubic foot of water.
How do you convert gallons back into cubic feet?▼
Divide the number of gallons by 7.480519 (or multiply gallons by 0.133681).
Does temperature change how many gallons fit in a cubic foot?▼
Volume remains fixed at 7.4805 gallons per cubic foot. However, water density changes slightly with temperature (warm water expands slightly and weighs less per gallon).
Authoritative Sources & Reference Standards
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811 — National Institute of Standards and Technology (NIST). Verified 2026-10-01.
Official SI unit definitions, conversion factors (Appendix B), and precision standards for cubic meters, liters, and US customary units.
- The International System of Units (SI Brochure, 9th edition) — Bureau International des Poids et Mesures (BIPM). Verified 2026-10-01.
International metric definitions for derived units of volume (cubic meter and non-SI unit accepted for use: liter).