Answer first
What this calculator tells you
Calculate cubic feet, liters and gallons from a length, a width and a height in any common unit. Find the volume of a box, a bin, a room or a tank from three measurements. Formula: Cubic feet = length × width × height, after converting each to feet. At the worked-example inputs, the cubic feet is 12. Holding every other input steady, moving length from 38 to 58 moves the result from 9.5 to 14.5.
Transparent method
The formula
Find the volume of a box, a bin, a room or a tank from three measurements.
Worked example
Example inputs
How to interpret the result
Volume is length times width times height in the same unit. A 48 by 24 by 18 inch box is 20,736 cubic inches, which is 12 cubic feet. At 7.48 gallons per cubic foot, that box holds about 90 gallons, or 340 liters.
At the worked-example inputs the cubic feet is 12. It rises with height, length and width and falls as unit of measure increases.
These are material-quantity estimates. Always add a waste and overage margin, and confirm actual coverage with your specific product and supplier before purchasing.
Before you rely on it
What to check
Pick the unit you measured in and the calculator converts each side to feet first. Do not mix units, because 4 feet by 30 inches is not 120.
The common error
Where people go wrong with cubic feet calculator
Using the outside size of a container. Walls take space, so the usable volume of a tank or a bin is smaller than its outer dimensions suggest.
Sensitivity evidence
How length changes the cubic feet
Holding every other input at the worked-example value, moving length from 38 to 58 moves the cubic feet from 9.5 to 14.5: a spread of 5, or 42% of the worked-example result.
| Length | Cubic feet | Liters | US gallons |
|---|---|---|---|
| 38 | 9.5 | 269 | 71.1 |
| 43 | 10.7 | 304.4 | 80.4 |
| 48worked example | 12 | 339.8 | 89.8 |
| 53 | 13.2 | 375.2 | 99.1 |
| 58 | 14.5 | 410.6 | 108.5 |
Every input, tested
Which input moves the cubic feet most
Of the 4 inputs, unit of measure moves the cubic feet most (11.3 across the range tested) and width moves it least (2).
| Input | Tested from | To | Cubic feet at each end | Swing |
|---|---|---|---|---|
| Unit of measure | Inches | Centimeters | 12 to 0.732 | 11.3 (6102368%) |
| Height | 16 | 20 | 10.7 to 13.3 | 2.7 (22%) |
| Length | 43 | 53 | 10.7 to 13.2 | 2.5 (21%) |
| Width | 22 | 26 | 11 to 13 | 2 (17%) |
Two variables at once
Cubic feet by length and width
Across the grid the cubic feet runs from 7.5 to 17.5. Moving length from 38 to 58 shifts it by 5 at the middle column, and moving width from 19 to 29 shifts it by 5 at the middle row, so neither is the bigger lever here.
| Length \ Width | 19 | 24 | 29 |
|---|---|---|---|
| 38 | 7.5 | 9.5 | 11.5 |
| 43 | 8.5 | 10.7 | 13 |
| 48 | 9.5 | 12 | 14.5 |
| 53 | 10.5 | 13.2 | 16 |
| 58 | 11.5 | 14.5 | 17.5 |
The highlighted cell is the worked example: 12.
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Length | 48 | Enter the length used in this calculation. |
| Width | 24 | Enter the width used in this calculation. |
| Height | 18 | Enter the height used in this calculation. |
| Unit of measure | Inches | The unit you measured in. |
| Cubic feet | 12 | |
| Liters | 339.8 | |
| US gallons | 89.8 | |
Inputs, definitions and assumptions
Length
Enter the length used in this calculation. The prefilled worked-example value is 48.
Width
Enter the width used in this calculation. The prefilled worked-example value is 24.
Height
Enter the height used in this calculation. The prefilled worked-example value is 18.
Unit of measure
The unit you measured in. The prefilled worked-example value is Inches.
How to use this calculator
- 1Verify the inputs. Gather length, width, height and unit of measure from your own documents; the prefilled values are examples.
- 2Save a baseline. The worked example puts the cubic feet at 12. Store your own version of it as Scenario A.
- 3Test one change. Start with unit of measure, the input with the biggest effect here: switching unit of measure changes the cubic feet: inches gives 12; feet gives 20,736; yards gives 559,872; meters gives 732,284.9; centimeters gives 0.732.
- 4Check the boundary. Read the interpretation boundary above before acting on the result.
People also ask
Frequently asked questions
How do you calculate cubic feet?
Cubic feet = length × width × height, after converting each to feet. At the worked-example inputs the cubic feet is 12.
What does the cubic feet result mean?
Find the volume of a box, a bin, a room or a tank from three measurements. At the worked-example inputs the cubic feet is 12. It rises with height, length and width and falls as unit of measure increases.
How much does length change the cubic feet?
Holding every other input at the worked-example value, moving length from 38 to 58 moves the cubic feet from 9.5 to 14.5, a spread of 5.
What are the limits of this cubic feet calculator?
These are material-quantity estimates. Always add a waste and overage margin, and confirm actual coverage with your specific product and supplier before purchasing. The tables on this page test length only from 38 to 58; a value outside that range is not tabulated here.
Which input moves the cubic feet most in the cubic feet calculator?
Ranked by how far each moves the cubic feet across the range tested: unit of measure (11.3, 6102368%), height (2.7, 22%), length (2.5, 21%) and width (2, 17%).
How much does width matter in the cubic feet calculator?
The worked example uses 24. Holding every other input at its worked-example value, moving width from 22 to 26 takes the cubic feet from 11 to 13, a swing of 17% of the worked-example figure.
How much does height matter in the cubic feet calculator?
The worked example uses 18. With the other inputs left at the worked example, moving height from 16 to 20 takes the cubic feet from 10.7 to 13.3, a swing of 22% of the worked-example figure.
How much does unit of measure matter in the cubic feet calculator?
The worked example uses Inches. Holding every other input at its worked-example value, switching unit of measure changes the cubic feet: inches gives 12; feet gives 20,736; yards gives 559,872; meters gives 732,284.9; centimeters gives 0.732.
Which inputs change the liters in the cubic feet calculator?
At the worked-example inputs it is 339.8. Length takes it from 304.4 to 375.2, width takes it from 311.5 to 368.1, height takes it from 302 to 377.6 and unit of measure takes it from 339.8 to 20.7.
Which inputs change the US gallons in the cubic feet calculator?
At the worked-example inputs it is 89.8. Length takes it from 80.4 to 99.1, width takes it from 82.3 to 97.2, height takes it from 79.8 to 99.7 and unit of measure takes it from 89.8 to 5.5.
Why should I round up a material estimate?
Real coverage is never perfectly uniform: uneven ground, waste from cutting, and spillage all consume more material than the flat geometric calculation suggests. Rounding up avoids a second supply trip, which usually costs more in time than the extra material costs in money.
Sources and evidence
Free Calculators Online is independent and is not affiliated with or endorsed by the source organizations. Educational estimates only.