Cube Root Calculator

What a Cube Root Means

A cube root undoes cubing. Since $3 \times 3 \times 3 = 27$, the cube root of 27 is 3.

The name comes from volume. $\sqrt[3]{n}$ is the edge length of a cube whose volume is $n$ - exactly what the figure shows. So “what is $\sqrt[3]{64}$?” is the same as asking “how long is each edge of a cube that holds 64 unit cubes?” The answer is 4, because $4 \times 4 \times 4 = 64$.

Numbers like 8, 27, 64, and 125 are perfect cubes - their cube roots are whole. And unlike square roots, a cube root of a negative number is real: $\sqrt[3]{-27} = -3$, because $-3 \times -3 \times -3 = -27$.

Worked Examples

Number	Cube root
8	2
27	3
64	4
-27	-3
50	3.684

FAQ

What is a cube root?

The cube root of n is the number that cubes to n. $\sqrt[3]{27} = 3$ because $3 \times 3 \times 3 = 27$.

Can you take the cube root of a negative number?

Yes. $\sqrt[3]{-27} = -3$, because $-3 \times -3 \times -3 = -27$. This differs from square roots, which have no real value for negatives.

What is a perfect cube?

A number whose cube root is a whole number, like 8, 27, 64, and 125. The tool flags these.