How this calculator works
The volume of a box is its length times its width times its height. A cylinder is π times the radius squared times the height, and a sphere is 4/3 times π times the radius cubed. With the dimensions in feet the result is in cubic feet, which converts to cubic yards (divide by 27), US gallons (multiply by 7.48), liters (multiply by 28.3) and cubic meters (multiply by 0.0283).
Worked example: a 10 × 8 × 6 ft box holds 480 cubic feet (17.78 cubic yards, 3,591 gallons). A cylinder 4 ft across and 6 ft high holds 75.4 cubic feet (564 gallons), and a sphere 4 ft across 33.5 cubic feet.
Common conversions
One cubic foot is
| Unit | In one cubic foot | One of this unit in cubic feet |
|---|---|---|
| Cubic inches | 1,728 | 0.000579 |
| Cubic yards | 0.0370 | 27 |
| US gallons | 7.481 | 0.1337 |
| Liters | 28.317 | 0.0353 |
| Cubic meters | 0.0283 | 35.315 |
Tips before you buy
- Divide cubic feet by 27 for cubic yards, the unit bulk soil, gravel and concrete are sold in.
- A cubic foot of water weighs about 62.4 pounds, and holds about 7.5 gallons.
- For an irregular shape, split it into boxes and cylinders, and add up the volumes.
- Measure inside dimensions for a container and outside dimensions for a space you will fill.
- Use the cubic yard or the concrete calculator when you need to allow for waste.
Tools & materials for this project
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Frequently asked questions
How do you calculate cubic feet?
Multiply length by width by height, all in feet. A box 10 × 8 × 6 ft is 480 cubic feet.
How many cubic feet are in a cubic yard?
27, because a yard is 3 ft and 3 × 3 × 3 = 27.
How many gallons are in a cubic foot?
About 7.48 US gallons. A cubic foot of water weighs about 62.4 pounds.
How do you find the cubic feet of a cylinder?
π × radius² × height. A cylinder 4 ft across and 6 ft high is 75.4 cubic feet.
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Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.