Calculate the volume in cubic feet of a box, cylinder, cone, sphere, or prism, with instant conversions to cubic yards, meters, and gallons.
Cubic Feet Formula
Cubic feet measures volume, so the formula depends on the shape you are measuring. Every dimension is converted to feet first, then multiplied. The calculator supports the shapes below.
Box: V = L * W * H
Cylinder: V = pi * (D/2)^2 * H
Cone: V = (1/3) * pi * (D/2)^2 * H
Sphere: V = (4/3) * pi * (D/2)^3
Triangular prism: V = (1/2 * b * h) * L
Capsule: V = pi * (D/2)^2 * L + (4/3) * pi * (D/2)^3
- V = volume in cubic feet (ft³)
- L = length, in feet
- W = width, in feet
- H = height or depth, in feet
- D = diameter, in feet (the radius is D/2)
- b = triangle base, in feet
- h = triangle height, in feet
- pi = 3.14159
For a box you multiply length, width, and height. For round shapes the calculator takes the diameter you enter, halves it to get the radius, and applies the matching volume formula. A cone holds one third of the cylinder that surrounds it, and a sphere uses the radius cubed. A triangular prism is the area of the triangle on the end multiplied by how far the prism runs. A capsule is a straight cylinder section with a half sphere added on each end. If a dimension is entered in inches, yards, meters, centimeters, or millimeters, it is converted to feet before the volume is found, so you can mix units across fields.
Cubic Foot Conversions and Common Container Sizes
One cubic foot equals the volume of a cube that is one foot on every side. Use the table below to convert a cubic foot result into other units.
| 1 cubic foot equals | Amount |
|---|---|
| Cubic inches | 1,728 in³ |
| Cubic yards | 0.03704 yd³ |
| Cubic meters | 0.02832 m³ |
| Liters | 28.317 L |
| US gallons | 7.4805 gal |
The next table lists rough cubic foot sizes that come up when you order materials or estimate storage space.
| Item | Approximate volume |
|---|---|
| Standard bag of mulch | 2 ft³ |
| Bag of concrete mix (60 lb) | 0.45 ft³ |
| Cubic yard of soil or gravel | 27 ft³ |
| Small moving box | 2 ft³ |
| Full size refrigerator interior | 20 to 25 ft³ |
Example Problems
Example 1. A storage box is 4 feet long, 3 feet wide, and 2 feet high. Multiply the three dimensions: 4 * 3 * 2 = 24 cubic feet. That box holds 24 ft³, which is the same as 24 / 27 = 0.889 cubic yards.
Example 2. A round tank has a diameter of 6 feet and a height of 10 feet. The radius is 6 / 2 = 3 feet. Volume = pi * 3^2 * 10 = 3.14159 * 9 * 10 = 282.7 cubic feet. Multiply by 7.4805 to get about 2,115 US gallons of capacity.
Frequently Asked Questions
How do you find cubic feet from inches?
Convert each measurement to feet by dividing by 12, then multiply length by width by height. You can also multiply the dimensions in inches and divide the result by 1,728, since there are 1,728 cubic inches in one cubic foot. The calculator does this for you when you set a field's unit to inches.
How many cubic feet are in a cubic yard?
There are 27 cubic feet in one cubic yard, because a yard is 3 feet and 3 * 3 * 3 = 27. To turn cubic feet into cubic yards, divide by 27. Many bulk materials such as soil, mulch, and gravel are sold by the cubic yard, so this conversion helps you order the right amount.
What is the difference between cubic feet and square feet?
Square feet measure area, which is length times width across a flat surface. Cubic feet measure volume, which adds height or depth to that area. If you only have two dimensions you get square feet, and once you include the third dimension you get cubic feet.
