Cube Root Calculator

Cube Root Calculator finds the cube root of any number and, with the root field, any nth root. Unlike a square root, a cube root works perfectly well on negative numbers: three negatives multiplied together give a negative, so the cube root of -64 is -4.

That asymmetry between odd and even roots is handled properly. An even root of a negative number has no real value and the calculator says 'not real' rather than returning a nonsense figure, which is what the naive power calculation would do. Odd roots of negatives are computed on the magnitude and the sign put back.

The nearest perfect cubes are shown because they are the quickest sanity check on any cube root. If the number lies between 27 and 64, the root lies between 3 and 4, and any answer outside that range is wrong.

The page shows its working, not just its answer. Where there is a formula it is printed with your own numbers substituted in, so you can check the result rather than take it on trust -- which is the difference between a calculator you can use for something that matters and one you cannot.

Everything runs inside your browser. What you type is never uploaded, never logged and never stored, and the calculator keeps working if your connection drops after the page has loaded.

• Shows cube root, nth root, perfect cube, the number cubed and check together, so you are not running it twice
• Prints the formula with your own figures substituted in
• Updates as you type, with no button to press and no page reload
• Copy the result in one click
• Free, no sign-up, and it runs entirely in your browser

The cube root calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Finding the side of a cube from its volume
• Taking a fifth or seventh root for a growth calculation
• Checking whether a number is a perfect cube
• Working with negative values where a square root fails