How to use the cubic feet calculator
- Pick the shape: a box or room, a cylinder, or several parts added together.
- Enter each measurement and choose its unit. You can mix feet, inches, yards, metres and centimetres; everything is converted for you.
- Read the volume in cubic feet, with cubic yards, cubic inches, gallons and litres.
Cubic feet formulas
Box: length × width × height (all in feet)
From inches: length × width × height ÷ 1,728
Cylinder: π × (diameter ÷ 2)² × height
Cubic yards = cubic feet ÷ 27; gallons = cubic feet × 7.48
Worked examples
A 6 × 4 × 3 ft storage box
- 6 × 4 × 3 = 72 cubic feet.
- 72 ÷ 27 = 2.67 cubic yards; 72 × 7.48 = 539 gallons.
A moving box 24 × 18 × 18 in
- 24 × 18 × 18 = 7,776 cubic inches.
- 7,776 ÷ 1,728 = 4.5 cubic feet.
Volume conversions
| 1 cubic foot equals | Amount |
|---|---|
| Cubic inches | 1,728 |
| Cubic yards | 0.037 (1/27) |
| US gallons | 7.48 |
| Litres | 28.32 |
| Cubic metres | 0.0283 |
Common mistakes to avoid
- Mixing units. Multiplying feet by inches gives nonsense; convert first or pick the unit beside each box.
- Dividing inches by 12 instead of 1,728. Volume has three dimensions: 12 × 12 × 12.
- Outside vs inside size. Walls and lids take up space.
Frequently asked questions
How do I calculate cubic feet?
Multiply length × width × height, with every measurement in feet. A box 6 ft long, 4 ft wide and 3 ft high is 6 × 4 × 3 = 72 cubic feet.
How do I calculate cubic feet from inches?
Multiply the three measurements in inches and divide by 1,728 (12 × 12 × 12). A box 24 × 18 × 12 in is 5,184 cubic inches, or 3 cubic feet. Or simply choose "in" for each measurement above.
How do I find the cubic feet of a cylinder?
π × radius² × height, in feet. A drum 2 ft across and 3 ft tall is 3.1416 × 1 × 3 = 9.42 cubic feet.
How many gallons are in a cubic foot?
About 7.48 US gallons, or 28.3 litres.
How many cubic feet are in a cubic yard?
27. Divide cubic feet by 27 to get cubic yards; our cubic feet to cubic yards converter does it in one step.
How many cubic feet is a room?
Length × width × ceiling height. A 12 × 14 ft room with an 8 ft ceiling is 1,344 cubic feet, which is useful for heating, air conditioning and dehumidifier sizing.