How to calculate cubic feet
Cubic feet is the volume of a box-shaped space: length × width × height, all in feet. A 3 × 4 × 5 ft space is 3 × 4 × 5 = 60 cubic feet (about 2.22 cubic yards). If your measurements are in inches, divide each by 12 first.
A worked example with mixed units: a box measuring 18 in × 24 in × 30 in becomes 1.5 ft × 2 ft × 2.5 ft, giving 1.5 × 2 × 2.5 = 7.5 cubic feet. Converting each side before multiplying is essential — dividing the finished answer by 12 gives a figure 144 times too large, which is the single most common mistake with this conversion.
For the same task from a slightly different angle, try the gallons to liters calculator.
How to use this calculator
Enter length, width and height in feet. The result shows cubic feet and cubic yards — useful for shipping, storage, appliances and material orders. For area-and-depth materials, see the square feet to cubic yards calculator.
Some useful reference volumes: a standard moving box is about 3 cubic feet, a large wardrobe box about 15, a domestic fridge 18–25, and a small removal van roughly 250. Comparing your total against these makes it easy to sanity-check a quote before you book anything.
For irregular spaces, split the room into rectangular blocks, work out each one separately and add the results. An L-shaped loft measuring 10 × 6 × 5 ft plus 4 × 3 × 5 ft comes to 300 + 60 = 360 cubic feet. Remember that quoted storage-unit sizes are usually floor area, so multiply by the ceiling height to compare like with like.
If you are checking your work, the acres to square feet calculator gives you a second reference point.
Frequently asked questions
- How do I calculate cubic feet?
- Multiply length × width × height in feet. A 3 × 4 × 5 ft space is 60 cubic feet.
- How do I convert inches to cubic feet?
- Divide each dimension in inches by 12 to get feet, then multiply them together.
- How many cubic feet in a cubic yard?
- 27 cubic feet make one cubic yard.
- What is 3x4x5 in cubic feet?
- 60 cubic feet.
- Do I need cubic feet or square feet?
- Use cubic feet when you are filling a space and square feet when you are covering one. Flooring, paint and turf are priced by square feet, while moving boxes, mulch, concrete and freight are priced by volume, so they need the height as well.