Measurement calculator
Cubic feet calculator
Enter dimensions in whatever units you measured in and get the volume in cubic feet, plus every conversion you are likely to need for ordering material.
Your project
Volume
40
cubic feet
- Cubic yards
- 1.481 cu yd
- Cubic inches
- 69,120 cu in
- Cubic metres
- 1.133 m³
- Litres
- 1,132.7 L
- US gallons
- 299.2 gal
- Footprint area
- 80 sq ft
For bulk material, remember suppliers quote cubic yards. Divide cubic feet by 27, or read the cubic yard line above.
The shareable link reopens this calculator with your exact inputs.
How to calculate cubic feet
Convert every dimension to feet first, then multiply length by width by height. A box measured in inches is divided by 12 in all three directions, or by 1,728 at the end — 24 x 18 x 12 inches is 5,184 cubic inches, which is exactly 3 cubic feet.
For a cylinder, the volume is π times the radius squared, times the height. A 3 ft diameter tube filled 4 ft deep holds 28.3 cubic feet: π x 1.5² x 4.
Mixed units are the usual source of error — a slab quoted as 10 ft by 8 ft by 4 inches is 10 x 8 x 0.333, which is 26.7 cubic feet, not 320. The calculator above handles the conversion so you never have to divide by 12 in your head on a job site.
When cubic feet is the unit you need
Bagged material is sold in cubic feet: mulch in 2 cu ft bags, garden soil in 1.5, compost and potting mix in 1 or 2. Knowing the cubic feet of a bed tells you the bag count directly.
Freight, storage and appliance capacity are also quoted in cubic feet. A standard moving box is about 3 cubic feet; a 10 ft by 10 ft storage unit with an 8 ft ceiling is 800.
Bulk material is quoted in cubic yards instead. There are 27 cubic feet in a cubic yard, so a mental divide-by-27 turns a cubic feet answer into an order you can phone in.
Cubic feet conversions
One cubic foot expressed in the other units used for material and freight.
| Unit | Equal to 1 cubic foot |
|---|---|
| Cubic inches | 1,728 |
| Cubic yards | 0.03704 (1 cu yd = 27 cu ft) |
| Cubic metres | 0.02832 |
| Litres | 28.317 |
| US gallons | 7.481 |
| Bags of mulch (2 cu ft) | 0.5 |
Cubic feet from a square foot area at depth
Multiply your area by the factor for the depth you are placing.
| Depth | Cu ft per sq ft | Cu ft per 100 sq ft | Cu yd per 100 sq ft |
|---|---|---|---|
| 0.5" | 0.0417 | 4.2 | 0.15 |
| 1" | 0.0833 | 8.3 | 0.31 |
| 2" | 0.1667 | 16.7 | 0.62 |
| 3" | 0.25 | 25 | 0.93 |
| 4" | 0.3333 | 33.3 | 1.23 |
| 6" | 0.5 | 50 | 1.85 |
| 12" | 1 | 100 | 3.7 |
Frequently asked questions
+How do you calculate cubic feet?
Multiply length by width by height with all three measurements in feet. If you measured in inches, divide the final answer by 1,728; if in centimetres, divide by 28,317.
+How many cubic feet are in a cubic yard?
Exactly 27. A cubic yard is a 3 ft cube, and 3 x 3 x 3 is 27 cubic feet.
+How many cubic feet is a 2 cubic foot bag of mulch?
Two, by definition — which is why 13.5 bags make a cubic yard. Bags are sold by loose volume before the material settles, so expect slightly less spread coverage than the label suggests.
+How do I convert square feet to cubic feet?
Square feet is area; cubic feet is area times depth. Multiply your square footage by the depth in feet — for a depth in inches, divide by 12 first. 200 sq ft at 3 inches deep is 200 x 0.25 = 50 cubic feet.
+How many cubic feet in a gallon?
A US gallon is 0.1337 cubic feet, so one cubic foot holds 7.48 gallons. For liquids, that conversion is more useful than cubic yards.