Cube Calculator

Volume, surface area and the space diagonal.

Volume, surface area and the space diagonal. Volume is s³ and surface area 6s², since a cube has six identical faces.

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

Side length

Volume (units³)

Surface area 54 units²

Volume27 units³

Surface area54 units²

Lateral (side) area36 units²

Base area9 units²

If units are cm0.027 litres

Face diagonal4.2426 units

Space diagonal5.1962 units

Volume is s³ and surface area 6s², since a cube has six identical faces. The space diagonal — corner to opposite corner through the middle — is s√3, which is what limits the longest object that fits inside: 5.1962 units here, not the 3 you might expect from the side alone.

How the Cube Calculator works

Volume is s³ and surface area 6s², since a cube has six identical faces. The figure people forget is the space diagonal (corner to opposite corner through the middle, at s√3) which is what actually limits the longest object that will fit inside.

Also known as: volume of a cube · surface area of a cube · cube volume formula · space diagonal of a cube

Where to go next

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

Rectangular Prism Calculator — Box volume, surface area and the diagonal that decides what fits.
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 cube?

Cube the side length. A side of 3 gives 27 cubic units.

What is the surface area of a cube?

Six times the side squared, because there are six identical square faces. A side of 3 gives 54 square units.

What is the space diagonal?

The longest line inside the cube, from one corner to the opposite one through the centre. It is s√3, so a cube of side 3 has a space diagonal of 5.196 — noticeably longer than the side or the face diagonal.

How many litres is my cube?

If you measure in centimetres, divide the volume by 1,000. A 10 cm cube is exactly one litre, which is how the litre is defined.

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