Construction & material calculator

Cubic feet calculator

Find cubic feet for a rectangular room, box, storage space, shipment, or material area. Mixed units are supported so an inch-based box height can be combined with dimensions recorded in feet or centimeters.

Mixed unitsFormula shownNo account required

Interactive Cubic feet calculator

Enter project measurements

Enter measurements and select Calculate.

How to use this calculator

  1. Use inside dimensions for usable container capacity.
  2. Use outside dimensions for occupied storage or shipping space.
  3. Select the correct unit for every field.
  4. Keep the cubic-foot result for small spaces or convert to cubic yards for bulk material planning.

Formula and method

Volume = length × width × height. After the dimensions are normalized, the result is converted to ft³, yd³, and m³.

Worked example

A box that is 4 ft long, 30 in wide, and 2 ft high contains 20 ft³. The 30 in width is first converted to 2.5 ft.

Assumptions and result interpretation

  • The object is treated as a rectangular prism.
  • Wall thickness, packaging, and unusable voids are not subtracted automatically.
  • The displayed gallons are not used because this tool is intended for spatial volume, not liquid capacity.

Common mistakes

  • Mixing inside and outside dimensions
  • Using square feet where a third dimension is required
  • Forgetting to convert inches
  • Assuming cubic feet directly indicate material weight

Methodology sources

Conversions use deterministic factors. Variable material properties are either visibly sourced and editable or left for the user to enter from the supplier.

Results are planning estimates. Confirm actual requirements with the appropriate supplier, contractor, engineer, building official, or other qualified professional.