Cube Root Calculator
Find the cube root of any number, positive or negative, to eight decimal places. For whole numbers you also get the simplified radical form, such as 3∛2 for ∛54, and a perfect-cube check.
- Simplified radical form
- 3∛2
- Perfect cube?
- No
- The number cubed
- 157,464
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter the number. Negative numbers are allowed.
- Read the decimal cube root.
- For a whole number, use the simplified radical form if you need an exact answer.
Worked examples
Cube root of 54
- Cube root
- 3.77976315
- Simplified radical form
- 3∛2
- Perfect cube?
- No
Cube root of −64
- Cube root
- -4
- Simplified radical form
- -4
- Perfect cube?
- Yes
Cube root of 10
- Cube root
- 2.15443469
- Simplified radical form
- ∛10
Simplifying a cube root
Pull out the largest perfect-cube factor. 54 = 27 × 2, so ∛54 = ∛27 × ∛2 = 3∛2 ≈ 3.7798.
The perfect cubes up to 10³ are 1, 8, 27, 64, 125, 216, 343, 512, 729 and 1,000.
Negative numbers and volumes
Unlike square roots, cube roots of negative numbers are real: (−4) × (−4) × (−4) = −64, so ∛−64 = −4.
The cube root turns a volume back into a side length. A cube that holds 1,000 cubic centimeters (one liter) has sides of ∛1000 = 10 cm.
Questions people ask
What is the cube root of 27?
3, because 3 × 3 × 3 = 27.
What is the cube root of 54?
About 3.7798, or exactly 3∛2.
What is the cube root of −64?
−4. A negative number has a negative cube root.
What is the cube root of 10?
About 2.1544. Ten is not a perfect cube and has no cube factor, so ∛10 cannot be simplified.