Cube Root Calculator
Enter a number to get its real cube root, the number that multiplied by itself three times gives your value.
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Formula
cube root of x = x^(1/3), the real number y such that y × y × y = x. It works for negative x too.
Worked example
The cube root of 2: 1.26³ = 2.000376, so the root is just under 1.26. The exact value is 1.259921. For 27 the root is exactly 3, since 3 × 3 × 3 = 27, so 27 is a perfect cube.
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 because 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 because (-2) × (-2) × (-2) = -8.
How do I estimate a cube root by hand?
Find the two perfect cubes around your number. For 10, 2³ = 8 and 3³ = 27, so the root is a little above 2. The exact value is about 2.154435.
What is a perfect cube?
A perfect cube is the cube of a whole number, such as 1, 8, 27, 64 or 1000. Their cube roots are whole numbers: 1, 2, 3, 4 and 10.