Finds the cube root of any number — the value that, multiplied by itself three times, gives the original number.
How it works
The calculator raises the number to the power of one-third, correctly handling negative inputs since cube roots of negative numbers are real (unlike square roots).
What this does not include
This does not include square roots — for those, use this site’s square root calculator instead, which behaves differently for negative inputs.
How to use this calculator
- Enter any number, positive or negative.
A worked example
∛27 = 3, since 3 × 3 × 3 = 27. ∛(−8) = −2, since −2 × −2 × −2 = −8.
What the variable means
| Variable | Meaning |
|---|---|
| x | Any real number — the value to find the cube root of |
Edge cases worth knowing
Cube root is defined for negative numbers, unlike square root. Three negatives multiply to a negative (so a real cube root of a negative number always exists), while two negatives multiply to a positive (so no real square root exists for a negative number).
The cube root of 0 is 0 — the one case where the input and output coincide alongside 1 and −1.
Frequently asked questions
Why can you take the cube root of a negative number, but not the square root?
A negative number cubed gives a negative result (since three negatives multiply to a negative), so a real cube root always exists — squaring two negatives always gives a positive, so no real square root exists for negative numbers.
What is a “perfect cube”?
A number that’s the cube of a whole number, like 27 (3³) or 64 (4³) — its cube root comes out as a whole number too.
Where is cube root commonly used?
Finding the side length of a cube from its volume, or solving certain algebraic and geometric problems involving cubic relationships.
