Rex says
The fast lane for the math you almost remember from school. Type the numbers, get the answer, move on with your day.
Try a scenario
Click to load — tweak from there.Inputs
Result
nth root
9.000000
Note
Real root
Square root
27.000000
Cube root
9.000000
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter number.
- 2Enter root (n).
- 3Read your nth root on the right — it updates as you type.
- 4Hit Share to keep the scenario or send it to someone.
About this calculator
Handles any nth root, including odd roots of negative numbers, which are real even though a calculator that just uses Math.pow returns NaN.
Worked example
Using the values the calculator loads with:
Inputs
- Number: 729
- Root (n): 3
Results
- nth root: 9
- Note: Real root
- Square root: 27
- Cube root: 9
What each field means
Inputs
- Number
- The number used in the calculation. Starts at 729 so you have a working example on load.
- Root (n)
- The root (n) used in the calculation. Starts at 3 so you have a working example on load.
Results
- nth root
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Note
- Returned as a plain value. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Square root
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Cube root
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the root calculator work?
Handles any nth root, including odd roots of negative numbers, which are real even though a calculator that just uses Math.pow returns NaN. The underlying maths is: nth root of x = x^(1/n).
What do I need to enter?
2 values: number, and root (n). Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the nth root result mean?
It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Results are rounded for display; the underlying calculation keeps full precision.
Who is this tool for?
It's built for students, developers, and anyone who needs the answer right now without setting up a spreadsheet.
Accuracy and limitations
- Results are rounded for display; the underlying calculation keeps full precision.
- Very large or very small inputs may hit floating-point limits in the browser.
- Inputs outside the accepted range are clamped rather than rejected.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Root Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/root
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/root" target="_blank" rel="noopener">Root Calculator — RevenueLab</a> (2026).</p>
Source: [Root Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/root) (2026).