Cube Root Calculator

Find the real cube root of any positive, negative, or decimal number instantly.

Calculate a cube root
Enter any real number to find the value that cubes back to it.

About cube roots

The cube root of a number is the value that produces the original number when multiplied by itself three times. For example, the cube root of 27 is 3 because 3 times 3 times 3 equals 27. Cube roots reverse the operation of raising a number to the third power, just as square roots reverse squaring. The cube-root symbol is often read as the third root. Unlike an even root, a real cube root exists for every real number. Positive inputs have positive cube roots, zero has a cube root of zero, and negative inputs have negative cube roots. The cube root of negative 64 is negative 4 because multiplying negative 4 three times gives negative 64. This odd-power behavior is why the calculator uses the real cube-root operation rather than a fractional-power expression that can behave unexpectedly for negative values in some software. Perfect cubes have integer cube roots. Common examples include 1, 8, 27, 64, 125, 216, 343, 512, 729, and 1000. Most other numbers produce irrational or nonterminating decimal roots. This calculator rounds the displayed value to a practical number of decimal places while retaining normal floating-point precision for the calculation. It also cubes the displayed internal result to show a verification value, making it easy to see the inverse relationship. Cube roots arise in geometry whenever volume determines a length. If a cube has volume 125 cubic centimeters, its edge is the cube root of 125, or 5 centimeters. They also appear in dimensional scaling, engineering formulas, algebraic equations, statistics, and scientific models. When all dimensions of a similar solid scale together, volume changes by the cube of the scale factor, so recovering the linear scale requires a cube root. Enter integers, decimals, or negative values directly. Scientific notation accepted by the browser can also be useful for very large or very small magnitudes.

Cube root examples

Perfect cubes return exact integers, while other inputs usually return rounded decimals.

NumberCube rootExplanation
273Three cubed equals twenty-seven.
-64-4A negative number has a negative real cube root.
21.2599210499The cube root is irrational and displayed as a decimal.
0.0010.1One tenth cubed equals one thousandth.

How to find a cube root

  1. Enter the real number whose cube root you need.
  2. Select Calculate Cube Root to apply the real cube-root operation.
  3. Read the result and use the verification value to confirm that cubing it returns the input.

Frequently asked questions

Can a negative number have a cube root?

Yes, every negative real number has one negative real cube root. Cubing a negative value preserves its negative sign.

What is a perfect cube?

A perfect cube is the product of an integer multiplied by itself three times. Its cube root is therefore an integer.

Is a cube root the same as dividing by three?

No, a cube root reverses cubing rather than ordinary multiplication by three. Dividing 27 by three gives 9, while its cube root is 3.

Why is the answer rounded?

Many cube roots are irrational numbers with infinitely many nonrepeating digits. The calculator displays a rounded decimal that is convenient to read and use.

How does cube root relate to cube volume?

A cube volume equals its edge length cubed. Taking the cube root of the volume therefore recovers the edge length.