Gallons to Cubic Feet Converter
Convert US gallons (gal) to cubic feet (ft³)
Gallon (US)
Definition: The US gallon is a unit of volume used primarily in the United States for measuring liquids. One US gallon is defined as exactly 231 cubic inches, which is equivalent to approximately 0.133681 cubic feet. The gallon is the largest standard liquid measurement in the US customary system.
History/origin: The gallon has ancient origins dating back to Roman times. The US gallon was standardized in 1832 and is based on the wine gallon, defined as exactly 231 cubic inches. This precise cubic inch definition is the direct link used when converting gallons to cubic feet (231 ÷ 1,728 = 0.133681 ft³).
Current use: The US gallon is commonly used for measuring gasoline, water, and other liquids. Converting gallons to cubic feet is especially useful in plumbing, aquarium sizing, pool capacity calculations, HVAC systems, and civil engineering where volume is expressed in cubic feet.
Cubic Foot (ft³)
Definition: The cubic foot is a unit of volume in the US customary and imperial measurement systems. It is defined as the volume of a cube with sides measuring exactly one foot (12 inches) in length. One cubic foot equals 1,728 cubic inches, approximately 7.48052 US gallons, or 28.3168 liters.
History/origin: The cubic foot has been in use since the early development of the imperial measurement system. As a derived unit of the foot — itself one of the oldest length units — the cubic foot became a natural standard for measuring larger volumes in construction, engineering, and natural resource contexts. It remains widely used in countries that use the imperial or US customary systems.
Current use: The cubic foot is commonly used in construction and real estate (measuring room volumes and airflow), refrigerator and freezer capacity ratings, natural gas billing (hundred cubic feet = CCF), aquarium and pool sizing, shipping container volumes, and civil engineering projects. It is particularly useful when dealing with three-dimensional spaces where length measurements are already in feet.
Gallon to Cubic Foot Conversion Table
| Gallon [gal] | Cubic Foot [ft³] |
|---|---|
| 1 gal | 0.133681 ft³ |
| 2 gal | 0.267361 ft³ |
| 5 gal | 0.668403 ft³ |
| 7.48052 gal | 1 ft³ |
| 10 gal | 1.336806 ft³ |
| 20 gal | 2.673611 ft³ |
| 50 gal | 6.684028 ft³ |
| 100 gal | 13.368056 ft³ |
| 500 gal | 66.840278 ft³ |
| 1,000 gal | 133.680556 ft³ |
How to Convert Gallons to Cubic Feet
Formula:
1 gal = 0.13368055556 ft³
1 ft³ = 7.48051948 gal
Derivation:
Since 1 gallon = 231 cubic inches, and 1 cubic foot = 1,728 cubic inches:
1 gal = 231 ÷ 1,728 ft³ = 0.133681 ft³
Useful Relationships:
1 ft³ ≈ 7.481 gallons
1 ft³ = 1,728 in³ = 28.3168 L = 28,316.8 mL
100 gal ≈ 13.37 ft³
Examples:
Convert 10 gallons to cubic feet:
10 gal × 0.133681 = 1.33681 ft³
This is 1.337 cubic feet (e.g., a 10-gallon aquarium)
Convert 55 gallons to cubic feet:
55 gal × 0.133681 = 7.352 ft³
This is 7.352 cubic feet (standard 55-gallon drum)
Convert 1,000 gallons to cubic feet:
1,000 gal × 0.133681 = 133.681 ft³
This is 133.681 cubic feet (useful for large tank or pool calculations)