HowMuchIt / Cubic feet
How do I calculate cubic feet?
Multiply length, width and height, all in feet. The calculator also takes inches, does cylinders, and gives the answer in cubic yards and gallons.
Work out the cubic feet
| Step | How |
|---|---|
| Box | length x width x height |
| Cylinder | 3.14 x radius x radius x height |
| From inches | cubic inches / 1,728 |
| Cubic yards | cubic feet / 27 |
| Gallons | cubic feet x 7.48 |
Same unit, every side
Volume only works when all three sides use the same unit. In feet, the answer is cubic feet. If you measured in inches, multiply them and divide by 1,728, the cubic inches in a cubic foot. Concrete, soil and gravel are sold by the cubic yard: divide cubic feet by 27. For a tank or a tube, use the cylinder: 3.14 times the radius times the radius times the height, where the radius is half the diameter.
Questions people ask
How many cubic feet in a 10 x 10 x 8 room?
800 cubic feet, about 29.6 cubic yards.
How many gallons in a cubic foot?
About 7.48.
Good to know
- Volume of a box or room: length x width x height, all in the same unit; in feet the answer is cubic feet.1,2
- One cubic foot is 1,728 cubic inches, so cubic inches / 1,728 = cubic feet.3,4
- One cubic yard is 27 cubic feet; divide cubic feet by 27 to get cubic yards.1,2,3,5
- Cylinder volume: pi x radius x radius x height, where radius = diameter / 2.2,6
- One cubic foot holds about 7.48 US gallons.3,7
How we checked this page
Checked on October 27, 2026. We kept a fact only when two independent publishers agree, and each one is numbered to its sources below. Where sources give different numbers, we keep only what they share. We never write a price. This page was written with an AI assistant and checked against the sources below.
Sources
- Concrete Calculator - How Much Concrete Do I Need?, The Concrete Network
- How to Calculate Concrete Yardage, Vertigraph (Construction Master)
- Volume Units Converter, The Engineering ToolBox
- Cubic foot, Wikipedia (unit definition)
- Cubic Yard - CADC Construction Glossary, Auburn University
- Calculating Pool Volume, Leslie's
- Cubic Feet to Gallons Converter, Inch Calculator