Surface Area of a Cube Formula

Geometry Formulas: Area, Volume, Perimeter
Formula:

What is the formula for the surface area of a cube?

Answer

Surface area of a cube
S = 6 · a²

Here a is the side (or base). The result comes out in square units.

Where the formula comes from

S = 6 · a²

Six identical square faces, each of area a². Unfold the cube into a cross of six squares and the formula is simply counting them.

Worked examples

Let a = 4. Then the surface area of a cube = 96 square units.

Let a = 2.5. Then the surface area of a cube = 37.5 square units.

The common mistake

Writing 6a instead of 6a². Each face is a square, so the side is squared first and multiplied by six after.

Other quantities: Cube

See Also

Geometry Formulas: Area, Volume, Perimeter

These are the formulas for the area, perimeter, circumference, volume and surface area of the standard shapes — 31 of them. Each page shows not only the formula but where it comes from, what every letter stands for, two worked examples and the mistake that this particular shape invites. For example, it can help you find out what is the formula for the surface area of a cube? (The answer is: S = 6 · a²). Pick the pair — "Area of a circle", for instance — and hit the "Find out" button.
Geometry Formulas: Area, Volume, Perimeter
Formula:

Values from the Formula

If a =Surface area
16 square units
224 square units
354 square units
496 square units
5150 square units
10600 square units

FAQ

What is the formula for the surface area of a cube?

Surface area of a cube S = 6 · a²

Where does this formula come from?

Six identical square faces, each of area a². Unfold the cube into a cross of six squares and the formula is simply counting them.

What is the most common mistake here?

Writing 6a instead of 6a². Each face is a square, so the side is squared first and multiplied by six after.

How do I use this formula?

Put your own numbers in place of the letters. With a = 2.5, for instance, the formula S = 6 · a² gives = 37.5 square units.