How to calculate cubic feet
Cubic feet measure volume: how much space a three-dimensional object or room takes up. For any rectangular space, the formula is:
Cubic feet = Length (ft) × Width (ft) × Height (ft)
- Measure the length, width, and height of the space.
- Convert every measurement to feet (inches ÷ 12, yards × 3, meters × 3.281).
- Multiply the three numbers together. The result is the volume in cubic feet (ft³).
Worked examples
| Space | Dimensions | Calculation | Volume |
|---|---|---|---|
| Bedroom | 12 ft × 10 ft × 8 ft | 12 × 10 × 8 | 960 ft³ |
| Living room | 18 ft × 14 ft × 9 ft | 18 × 14 × 9 | 2,268 ft³ |
| Raised garden bed | 8 ft × 4 ft × 1 ft | 8 × 4 × 1 | 32 ft³ (1.19 yd³) |
| Moving box | 18 in × 18 in × 16 in | 5,184 ÷ 1,728 | 3 ft³ |
Measuring in inches
For boxes, appliances, and furniture you'll usually measure in inches. Multiply the three inch measurements, then divide by 1,728 — the number of cubic inches in one cubic foot (12 × 12 × 12). A 30 × 20 × 16 inch moving box is 9,600 cubic inches, or about 5.6 cubic feet.
Other shapes
- Cylinder (round planter, tank, column): π × radius² × height.
- Triangular prism (attic space under a gable roof): ½ × base × height of the triangle × length.
- L-shaped room: split it into two rectangles, calculate each, and add the results.
Cubic feet conversions
- 1 cubic foot = 1,728 cubic inches
- 1 cubic yard = 27 cubic feet
- 1 cubic meter = 35.315 cubic feet
- 1 cubic foot = 7.48 US gallons = 28.32 liters