How to use this calculator
- Enter your own values in the labeled fields. Check the units and assumptions before comparing results. Only the fields needed for your selected calculation mode are shown.
- Your answer updates automatically. Review the calculation steps to see exactly how it was calculated.
- Copy, share, save, or download your result. Saved inputs stay on this device.
How the calculation works
Use the radius, not diameter, for round shapes. Heights are perpendicular to the base; slant height is not interchangeable. The unit selector labels the entered dimensions; changing it does not convert existing numbers. Review the units, period and assumptions before comparing scenarios. Displayed values are rounded, while the underlying calculation retains its available precision.
A worked example
A rectangular prism measuring 3 × 4 × 5 feet contains 60 cubic feet.
Reading your result
Use the main result together with its units and supporting figures. Display values are rounded; calculations keep their underlying precision. A change in inputs or assumptions can change the answer. Compare the step-by-step working with your intended use before relying on an estimate.
Frequently asked questions
What assumptions does this calculation use?
Use the radius, not diameter, for round shapes. Heights are perpendicular to the base; slant height is not interchangeable. The unit selector labels the entered dimensions; changing it does not convert existing numbers.
Can I save or check a scenario?
The result includes the working and supporting values. Save and Restore keep inputs on this device; Copy, Download and Print export the result. Sharing a scenario explicitly includes the inputs in its link.
Sources & methodology
This calculator uses the mathematical identity and assumptions stated above. No current rates, prices, or external data are loaded. Conversion tools use international unit definitions.
Formula review: October 24, 2026. Read our methodology.