Cubic Feet Calculator
Area 1
Sample shape, not to scale.
Area __n__
Sample shape, not to scale.
No result yet. Enter length, width and height.
Price
Optional. The cost is the cu ft figure, rounded up to 0.01, times your price.
How this is calculated
How to calculate cubic feet
Cubic feet say how much space something holds or takes up. Bagged soil, mulch and concrete mix are labelled in cubic feet, so this is the number to carry to the store when you are filling a container.
- Box: length × width × height, each in feet.
- Cylinder: π × (diameter ÷ 2)² × height.
All three measurements have to be in feet before they are multiplied. An 18 in deep planter is 1.5 ft deep. Multiplying feet by inches gives an answer twelve times too large, which is the usual way this sum goes wrong.
The line under the result shows the same space in cubic yards, which is the cubic feet divided by 27.
Examples
Planter box: 4 ft × 2 ft × 1 ft 6 in
- Area: 4 ft × 2 ft = 8 sq ft = 0.74 m²
- Volume: 8 sq ft × 1 ft 6 in = 12.0 cu ft = 0.44 cu yd
12.0 cu ft. Cubic yards: 0.44 cu yd. Cubic meters: 0.340 m³.
Round planter: 2 ft × 1 ft 6 in
- Area: π × (2 ft ÷ 2)² = 3.1 sq ft = 0.29 m²
- Volume: π × (2 ft ÷ 2)² × 1 ft 6 in = 4.7 cu ft = 0.17 cu yd
4.7 cu ft. Cubic yards: 0.17 cu yd. Cubic meters: 0.133 m³.
Cubic feet of common box and cylinder sizes
| Shape and size | Cubic feet | Cubic yards | Cubic meters |
|---|---|---|---|
| Box: 2 ft × 2 ft × 2 ft | 8.0 cu ft | 0.30 cu yd | 0.227 m³ |
| Box: 3 ft × 3 ft × 3 ft | 27.0 cu ft | 1.00 cu yd | 0.765 m³ |
| Box: 6 ft × 3 ft × 2 ft | 36.0 cu ft | 1.33 cu yd | 1.019 m³ |
| Box: 8 ft × 4 ft × 1 ft | 32.0 cu ft | 1.19 cu yd | 0.906 m³ |
| Cylinder: 1 ft 6 in × 2 ft | 3.5 cu ft | 0.13 cu yd | 0.100 m³ |
| Cylinder: 2 ft × 3 ft | 9.4 cu ft | 0.35 cu yd | 0.267 m³ |
Questions
How do I get cubic feet from measurements in inches?
Type the inches into the inches boxes and leave the feet boxes empty. By hand, multiply the three measurements in inches and divide by 1,728, which is 12 × 12 × 12.
How many bags will fill my planter or raised bed?
Bagged soil and mulch state their volume in cubic feet on the front. Divide the cubic feet you need by that number and round up. A 12 cu ft planter takes six bags of 2 cu ft.
What is the difference between square feet and cubic feet?
Square feet measure a surface, two measurements multiplied. Cubic feet measure a space, three measurements multiplied. A floor has square feet. The room above it has cubic feet.
My pot is wider at the top than at the bottom. What do I enter?
There is no tapered shape here. Enter the cylinder with the diameter measured halfway up the side. That gives a figure close to the real volume and slightly below it.
Can I enter meters and still get cubic feet?
Yes. Switch to metric and enter meters. The main number stays in cubic feet, because that is what this page is for, and the cubic-meter line shows the metric volume.
Does height mean the same as depth?
Yes. It is the third measurement, whichever way the space faces. For a planter it is how deep the soil will be, which is usually less than the full height of the side.
Can it work out the cost?
Enter a price per cubic foot under Price. The cubic feet are rounded up to the next 0.01 and multiplied by your price. For bagged material, the bag count from the mulch, topsoil or concrete calculator times the shelf price is the closer figure, because bags are bought whole.
Related tools
Sources
Volume formulas for a box and a cylinder are plain geometry, so there is no publisher to cite for them. The unit figures are definitions. One foot is exactly 0.3048 m and 27 cubic feet make one cubic yard, both stated by NIST.
- NIST Handbook 44 (2024), Appendix C, General Tables of Units of Measurement, accessed October 8, 2026
- NIST Special Publication 811, Appendix B.9, conversion factors listed by kind of quantity, accessed October 8, 2026
Last reviewed: October 8, 2026