Cube Root Calculator
Enter any number below to instantly get its cube root.
What Is a Cube Root?
The cube root of a number n is the value x such that x³ = n. It's the inverse operation of cubing a number.
Unlike square roots, which only produce a real result from non-negative inputs, cube roots are defined for every real number — positive, negative, or zero — because a negative number cubed stays negative.
Worked example
Find the cube root of 64.
4 × 4 × 4 = 64
∛64 = 4
A second example
Find the cube root of −125.
(−5) × (−5) × (−5) = 25 × (−5) = −125
∛−125 = −5
Keep going
- Cube root and square root are the same radical idea at different degrees; the square root calculator handles the more common second-degree case. Square Root Calculator
Frequently Asked Questions
What is a cube root?
The cube root of a number is the value that, multiplied by itself three times, gives that number. The cube root of 27 is 3, since 3 × 3 × 3 = 27.
Can you take the cube root of a negative number?
Yes — unlike square roots, cube roots of negative numbers are real. The cube root of −8 is −2, since (−2) × (−2) × (−2) = −8.
How is a cube root different from a square root?
A square root undoes squaring (raising to the 2nd power); a cube root undoes cubing (raising to the 3rd power). Every positive number has one real cube root, while it has two square roots (one positive, one negative).
What are the first several perfect cubes?
1³ = 1, 2³ = 8, 3³ = 27, 4³ = 64, 5³ = 125, 6³ = 216, 7³ = 343, 8³ = 512, 9³ = 729, 10³ = 1000. Recognizing these makes it much faster to spot exact cube roots without a calculator.
Why do some calculators show an error for the cube root of a negative number?
Many basic calculators compute roots internally using logarithms, and logarithms are undefined for negative inputs — so they can't evaluate (−8)^(1/3) even though the real cube root, −2, clearly exists. A calculator built specifically for cube roots handles negative inputs directly instead.
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