Calculate length in feet from a volume in cubic feet using the width and height, or find cubic feet from length, width, and height.
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Cubic Feet to Feet Formula
Cubic feet measure volume and feet measure length, so you cannot convert one into the other without more information. To turn a volume in cubic feet into a length in feet, you divide the volume by the cross-sectional area (the width times the height):
L = V / (W * H)
To go the other way and find the volume in cubic feet from three measurements, multiply them together:
V = L * W * H
If the space is a perfect cube, the edge length is the cube root of the volume:
s = V^(1/3)
Where:
- V = volume in cubic feet (ft³)
- L = length in feet (ft)
- W = width in feet (ft)
- H = height in feet (ft)
- s = edge length of a cube in feet (ft)
The calculator has three modes. In the length mode you enter the volume in cubic feet plus the width and height, and it divides the volume by the cross-section to return the length. In the cubic feet mode you enter length, width and height and it multiplies them to return the volume. In the cube edge mode you enter only the volume and it takes the cube root to return the side length of a cube that holds that volume. The more options toggle lets you set how many decimal places the result uses.
Length in Feet for Common Cubic Foot Volumes
Because the length depends on the cross-section, the same volume gives a different length once the width and height change. This table shows the length in feet for a few volumes across common cross-sections.
| Volume (ft³) | Width × Height (ft) | Cross-section (ft²) | Length (ft) |
|---|---|---|---|
| 100 | 2 × 2 | 4 | 25 |
| 100 | 5 × 4 | 20 | 5 |
| 500 | 8 × 9 | 72 | 6.94 |
| 900 | 8 × 9 | 72 | 12.5 |
If the volume sits in a cube, the side length is fixed. This table lists the cube edge for common volumes.
| Volume (ft³) | Cube edge (ft) |
|---|---|
| 1 | 1 |
| 8 | 2 |
| 27 | 3 |
| 64 | 4 |
| 100 | 4.64 |
Example Problems
Example 1. You need to load 900 cubic feet of freight into a trailer that is 8 feet wide and 9 feet tall. The cross-section is 8 times 9, which is 72 square feet. The length is 900 divided by 72, which is 12.5 feet. So the load fills 12.5 feet of trailer length.
Example 2. You have 27 cubic feet of storage and want the side length of a cube that holds it. The cube edge is the cube root of 27, which is 3 feet. So a cube measuring 3 feet on every side holds 27 cubic feet.
Frequently Asked Questions
Can you convert cubic feet directly to feet? No. Cubic feet measure volume in three dimensions and feet measure length in one dimension. You can only find a length once you know the other two dimensions, either the width and height of the space or the assumption that the shape is a cube.
How do you convert cubic feet to linear feet? Divide the volume in cubic feet by the cross-sectional area in square feet. The cross-section is the width times the height. For example, 200 cubic feet through a 4 square foot opening is 200 divided by 4, which is 50 linear feet.
What is the difference between cubic feet and square feet? Cubic feet measure volume using three dimensions, length times width times height. Square feet measure area using two dimensions, length times width. To move from cubic feet toward a single length you remove two dimensions, and to reach square feet you remove one.
