Enter the dimensions of a box, room, tank or cylinder in inches, feet or centimeters to get cubic feet, plus cubic yards, gallons and liters.
How to use the cubic feet calculator
- Choose a box (anything with square corners, including rooms and truck beds) or a cylinder (drums, pipes, round tanks).
- Enter each measurement and its unit. Inside dimensions give the capacity; outside dimensions give the space an object takes up.
- Enter a quantity for several identical boxes or containers.
Cubic feet formulas
Box: cubic feet = length × width × height (all in feet) Cylinder: cubic feet = π × (diameter ÷ 2)² × height From inches: cubic feet = cubic inches ÷ 1,728 1 ft³ = 7.48052 US gallons = 28.3168 liters
A cubic foot is 12 × 12 × 12 = 1,728 cubic inches. The US gallon is defined as exactly 231 cubic inches, so a cubic foot holds 1,728 ÷ 231 = 7.48052 gallons.
Worked example: a moving box, 18 × 18 × 24 in
- Cubic inches: 18 × 18 × 24 = 7,776 in³.
- Cubic feet: 7,776 ÷ 1,728 = 4.5 ft³.
- A tank measuring 48 × 13 × 21 in inside holds 7.58 ft³, or 56.7 US gallons.
- A cylinder 22.5 in across and 33.5 in tall holds 7.71 ft³, or 57.7 gallons.
- A 12 × 14 ft room with an 8 ft ceiling has 1,344 ft³ of air, useful for ventilation and dehumidifier sizing.
Volume conversions
| 1 cubic foot equals | Value |
|---|---|
| Cubic inches | 1,728 |
| Cubic yards | 0.03704 |
| US gallons | 7.48052 |
| Liters | 28.3168 |
| Cubic meters | 0.028317 |
Where cubic feet come up
- Moving and storage: truck and unit sizes are often given in cubic feet; add up your boxes to compare.
- Appliances: refrigerator and freezer capacity is listed in cubic feet of inside space.
- Soil, mulch and concrete bags are labeled in cubic feet; the cubic yard calculator converts bigger jobs.
- Aquariums and tanks: multiply cubic feet by 7.48 for gallons.
Questions
How do I calculate cubic feet from inches?
Multiply length × width × height in inches, then divide by 1,728. An 18 × 18 × 24 in box is 4.5 ft³.
How many gallons are in a cubic foot?
7.48052 US gallons.
How do I find the cubic feet of a cylinder?
π × radius² × height, in feet. Measure the diameter, halve it for the radius, and use the Cylinder option above.
How many cubic feet are in a cubic yard?
27.
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Exact inch and foot definitions; cubic foot, cubic yard and gallon conversions.