Math
Rectangular Prism Volume Calculator
Use this rectangular prism volume calculator for boxes, rooms, tanks, and geometry problems with three perpendicular dimensions.
Use the longest edge or the edge labeled length in your diagram.
Keep this in the same unit as length and height.
Use the perpendicular vertical or depth dimension.
Volume
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- Volume
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- Surface area
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- Space diagonal
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Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
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Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the rectangular prism volume calculator solves
Use this rectangular prism volume calculator for boxes, rooms, tanks, and geometry problems with three perpendicular dimensions.
Formula
How to use it
- Enter the shape dimensions using one consistent unit system.
- Check the formula and supporting measures before copying the answer.
- Use square units for area results and cubic units for volume results.
How to read the answer
Volume counts how many unit cubes fit inside the prism, while surface area counts the outside wrapping area.
Common mistakes and edge cases
- Use three perpendicular dimensions.
- Do not mix inches, feet, centimeters, or meters in the same input set.
- Volume uses cubic units, not square units.
Worked examples
Storage box
Volume
Volume = 240 cubic units
Decimal dimensions
Volume
Volume = 57.6 cubic units
Impossible prism
Volume
Error
Frequently asked questions
Is a rectangular prism the same as a box?+
For geometry volume, yes. A box-shaped solid with rectangular faces is a rectangular prism.
How do I use feet and inches together?+
Convert all dimensions to one unit first, such as all inches or all feet, before calculating volume.
Why show the space diagonal?+
The diagonal tells you the longest straight object that could fit corner to corner inside the prism.
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Last updated: May 15, 2026