Cubic Feet Calculator
Calculate cubic volume from length, width and depth or height.
Project details
Enter your measurements below.
Use cubic feet when three dimensions matter
Square footage describes a surface; cubic feet describes space. This calculator is useful when you need the volume inside a rectangular box, room, container, storage bay or material section. Measure length, width and height in compatible units, multiply the three dimensions, and keep the result as a volume rather than treating it like an area. For irregular spaces, separate the project into rectangular blocks. The tool is deliberately general, so it does not assume whether the volume represents air, soil, concrete, storage or another material.
Three-dimensional rectangular volume, not floor or wall area.
Cubic feet can be converted to cubic yards when ordering bulk material.
Add several simple volumes instead of multiplying the largest overall dimensions.
How to use the Cubic Feet Calculator
- Measure the usable length and width of the space or object.
- Measure the height or depth that completes the three-dimensional volume. Use the same unit family for all dimensions before multiplying.
- If the shape changes depth or width, divide it into separate rectangular sections and calculate each section on its own.
- Add the section volumes, then convert to cubic yards, litres or another unit only if the next planning step requires it.
Why volume needs three dimensions
A cubic-foot result contains three-dimensional capacity. It should not be mixed with square footage unless a known depth is being applied to that area.
How to use the volume
Use the result as a clean capacity or material-volume number. If the job involves a bulk product, apply density, compaction, packaging or supplier ordering rules in the relevant material calculator.
Worked example: a storage box
- Inside length
- 4 ft
- Inside width
- 2.5 ft
- Inside height
- 3 ft
- Calculation
- 4 × 2.5 × 3
The internal volume is 30 cubic feet. If the same number were needed in cubic yards, 30 ÷ 27 is about 1.11 cubic yards. The calculation says nothing about the weight of what is placed inside.
Practical planning tips
Use inside dimensions for container capacity and outside dimensions for the space an object occupies; they answer different questions.
When one dimension is entered in inches, convert it before multiplying instead of treating 6 inches as 6 feet.
For an attic, crawlspace or tapered pile, a rectangular volume may overstate the real space. Split the shape or choose a shape-specific method.
Write the unit beside every dimension on your sketch. Most large volume errors are unit errors rather than multiplication errors.
Common mistakes to avoid
Multiplying length by width and calling the answer cubic feet without including height or depth.
Using 12 as the cubic-foot conversion factor. Twelve converts feet to inches; there are 27 cubic feet in one cubic yard.
Measuring a container externally when the goal is internal storage capacity.
Treating a cubic-foot material estimate as a weight estimate without a material density.
Cubic Feet Calculator FAQs
What is the difference between square feet and cubic feet?+
Square feet measures a two-dimensional surface. Cubic feet measures a three-dimensional volume and therefore needs length, width and height or depth.
How many cubic feet are in a cubic yard?+
There are 27 cubic feet in one cubic yard because a 3 ft × 3 ft × 3 ft cube contains 27 cubic feet.
Can I calculate room air volume with this tool?+
Yes, for a rectangular room. Multiply interior length, width and height. Complex vaulted spaces should be broken into simpler sections for a closer estimate.
Can cubic feet tell me how much material weighs?+
Not by itself. Weight depends on the material's bulk density and sometimes moisture or compaction.