What the cubic feet calculator does
Cubic feet is the everyday unit for smaller volumes in the US and Canada: bags of soil and mulch, storage space, appliance capacity, shipping cartons and room volume for heating or ventilation sizing. This calculator measures rectangular boxes and rooms, cylinders such as tanks and planters, or any area multiplied by a height.
Litres and cubic metres are shown alongside, which helps when comparing products labelled in metric. For example, a 50-litre bag of compost is about 1.77 cubic feet.
How to use it
- Choose the shape: box or room, cylinder, or area × height.
- Enter the measurements in any unit: inches, feet, millimetres, centimetres or metres.
- Set the quantity for several identical items.
- Use the quick converter to change a known volume into other units.
Cubic feet formulas
Box: Volume = Length × Width × Height
Cylinder: Volume = π × (Diameter ÷ 2)² × Height
Measure in feet to get cubic feet directly. If you measured in inches, divide the result by 1,728 (12 × 12 × 12).
| 1 cubic foot equals | Value |
|---|---|
| Cubic inches | 1,728 |
| Cubic yards | 0.037037 (1 ÷ 27) |
| Litres | 28.3168 |
| Cubic metres | 0.0283168 |
| US gallons | 7.4805 |
| UK gallons | 6.2288 |
Worked examples
- Storage chest 4 ft × 3 ft × 2 ft = 24 ft³ (0.89 yd³, 680 litres).
- Shipping box 18 × 12 × 10 in = 2,160 in³ ÷ 1,728 = 1.25 ft³ (35.4 litres).
- Round planter 3 ft across and 2 ft deep: π × 1.5² × 2 = 14.14 ft³ (400 litres).
- Metric box 1.2 m × 1.0 m × 0.6 m = 0.72 m³ = 25.4 ft³.
Understanding the results
- Volume – total cubic feet (or cubic metres in metric mode) for all items.
- Cubic yards – useful when the volume is large enough to buy in bulk.
- Litres and gallons – capacity of tanks, containers and bags.
- Volume of one item – shown when quantity is more than one.
Measuring tips
- For containers, measure the inside dimensions to get usable capacity.
- For rooms, measure floor to ceiling; subtract large built-ins if you need air volume.
- For tapered planters, average the top and bottom diameters for an approximate volume.
- Keep all three measurements in mind: a single wrong unit (inches vs feet) changes the answer by a factor of 12.
Related tools
For bulk orders in cubic yards, use the cubic yard calculator. To fill garden beds with soil, the raised bed soil calculator handles multiple beds and bags. For concrete in bags, the concrete bag calculator converts cubic feet into bag counts.