Free Cubic Feet Calculator
Use this cubic feet calculator to work out the volume of any box, bed, room or round shape in cubic feet, cubic yards and cubic metres.
Cubic feet measure volume: how much space something takes up or holds. For a box shape, multiply length × width × height, with every measurement in feet.
If you measured in inches, multiply the three numbers and divide by 1,728 (12 × 12 × 12). For round shapes, choose Circle and enter the diameter. The calculator converts any mix of units for you.
How to calculate cubic feet: an example
A 4 × 3 ft box, 12 in high: 12 sq ft × 12 in ÷ 12 = 12 cu ft. Divide by 27 to get 0.44 cubic yards.
Typical heights to measure
| Use | Height (or depth) | Notes |
|---|---|---|
| Raised bed | 6 to 18 in | |
| Box or crate | Inside height | |
| Room or shed | Ceiling height | Enter it in feet. |
| Round planter or tube | Height | Choose the Circle shape. |
Cubic feet conversions
| From | To cubic feet |
|---|---|
| 1 cubic yard | 27 cu ft |
| 1 cubic metre | 35.31 cu ft |
| 1 cubic inch | 1/1,728 cu ft |
| 1 US gallon | 0.1337 cu ft |
| 1 litre | 0.0353 cu ft |
Coverage per cubic yard
| Height (or depth) | Sq ft per cubic yard |
|---|---|
| 1 in | 324 |
| 2 in | 162 |
| 3 in | 108 |
| 4 in | 81 |
| 6 in | 54 |
| 12 in | 27 |
| 24 in | 14 |
| 36 in | 9 |
Buying tips
- Mixing units is fine: enter length in feet and height in inches, and the calculator converts.
- For an irregular space, split it into rectangles, circles and triangles and add each one.
- Bagged soil and mulch are labelled in cubic feet, so this tells you directly how many bags fill a space.
Frequently asked questions
How do I calculate cubic feet?
Multiply length × width × height, all in feet. A box 4 ft long, 3 ft wide and 1 ft high holds 4 × 3 × 1 = 12 cubic feet.
How do I calculate cubic feet from inches?
Multiply the three measurements in inches and divide by 1,728. For example 24 × 18 × 12 in = 5,184 cubic inches ÷ 1,728 = 3 cubic feet.
How many cubic feet are in a cubic yard?
27 cubic feet.
How do I find the cubic feet of a cylinder?
Use π × radius² × height, in feet. In the calculator, choose Circle and enter the diameter; it does the rest.
How accurate is this cubic feet calculator?
The cubic feet calculator gives the exact volume for the measurements you enter, then adds 0% extra (you can change it). Measure carefully: an error of one inch in depth changes a 3 inch layer by a third.
How the cubic feet calculator works
Volume = area × height (or depth). Each area is worked out from its shape (length × width, π × radius², or ½ × base × height), converted to square feet, multiplied by the height (or depth) in feet, and added up. Cubic feet ÷ 27 = cubic yards.The extra percentage is then added, and bag counts are rounded up to whole bags. See how we calculate for every figure we use.