How to measure cubic feet
Measure the length, width and height, convert each to feet, and multiply. If you measured in inches, you can multiply the inches and divide by 1,728, because a cubic foot is 12 × 12 × 12 = 1,728 cubic inches.
Cubic feet = length (ft) × width (ft) × height (ft)
= length (in) × width (in) × height (in) ÷ 1,728
Round: π × (diameter ÷ 2)² × height
= length (in) × width (in) × height (in) ÷ 1,728
Round: π × (diameter ÷ 2)² × height
Worked examples
- A box 24 × 18 × 12 in: 24 × 18 × 12 = 5,184 cubic inches ÷ 1,728 = 3 cubic feet.
- A room 12 × 10 ft with an 8 ft ceiling: 12 × 10 × 8 = 960 cubic feet.
- A round tank 4 ft across and 3 ft deep: π × 2² × 3 = 37.7 cubic feet, about 282 gallons.
Cubic feet and square feet
Square feet measure area (flat); cubic feet measure volume (space). You can't convert one into the other without a depth: cubic feet = square feet × depth in feet.
Limitations
- Inside vs outside: for a box or tank, measure the inside to get what it holds.
- Irregular shapes: split them into boxes and cylinders and add the results.