Rectangular Prism Calculator

Box volume, surface area and the diagonal that decides what fits.

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Length

Width

Height

Volume (units³)

Surface area 52 units²

Volume24 units³

Surface area52 units²

Lateral (side) area28 units²

Base area12 units²

If units are cm0.024 litres

Space diagonal5.3852 units

Volume is length × width × height. Surface area is 2(lw + lh + wh) — three pairs of identical faces. The space diagonal of 5.3852 units is the longest straight object that fits inside, which is the figure that actually matters when checking whether something will go in a box.

How the Rectangular Prism Calculator works

Volume is length × width × height and surface area is 2(lw + lh + wh) — three pairs of identical faces. The space diagonal is the figure that matters in practice, because it is the longest straight object that will fit inside the box.

Also known as: volume of a box · cuboid calculator · box surface area calculator · rectangular prism volume

Where to go next

The Rectangular Prism question rarely arrives on its own. These are the ones that usually come with it:

Cube Calculator — Volume, surface area and the space diagonal.
Volume Calculator — Six shapes, with the litre conversion built in.
Surface Area Calculator — Six shapes, and the ratio that explains why small things cool fast.
Percentage Calculator — Every common percentage question in one place.

Sources

NIST Digital Library of Mathematical Functions

Frequently asked questions

How do I find the volume of a box?

Multiply length by width by height. A 4 by 3 by 2 box holds 24 cubic units.

How do I find the surface area?

Add the three distinct face areas and double the total, since each face has an identical partner opposite it. A 4 by 3 by 2 box has a surface area of 52 square units.

Will a long object fit in my box?

Compare it to the space diagonal, not to any single side. A 4 by 3 by 2 box has a diagonal of 5.39, so it takes something noticeably longer than its longest side.

What is a cuboid?

The same shape — a box with six rectangular faces. Cuboid is the more common term outside the United States.

Put this calculator on your own site

Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.

The one-line version

<iframe src="https://www.thecalclibrary.com/embed/rectangular-prism-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px" loading="lazy" title="Rectangular Prism Calculator"></iframe>
<p style="font:13px/1.5 system-ui,sans-serif;margin:6px 0 0;color:#64748b">Powered by <a href="https://www.thecalclibrary.com/rectangular-prism-calculator" style="color:#64748b">Rectangular Prism Calculator</a> from The Calc Library</p>

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