Math

Instant, private, and free

Fourth Root Calculator.

Calculate the principal real fourth root of a non-negative number.

On-device calculationNo signup
01

Set your values

Results update as you type.

Root: 3

Root

0.000000

Results update automatically as you type.

Use Cases

Solve math problems

Quickly find the fourth root for homework, exams, or everyday calculations without manual computation.

Example: Find the fourth root of 81 to solve an algebra problem.

Engineering and science calculations

Use the fourth root in formulas involving areas, volumes, or other power relationships where the fourth root is needed.

Example: Calculate the fourth root of a value in a physics formula.

Frequently Asked Questions

What is a fourth root?
The fourth root of a number x is a number y such that y^4 = x. For non-negative x, the principal fourth root is the non-negative y. For example, the fourth root of 16 is 2 because 2^4 = 16.
Can I calculate the fourth root of a negative number?
This calculator is designed for non-negative numbers only. The principal real fourth root of a negative number is not defined in real numbers because no real number raised to the fourth power gives a negative result.
How do I use this calculator?
Simply enter a non-negative number in the 'Number' field and click calculate. The calculator will instantly display the principal real fourth root of that number.

Tips & Common Mistakes

Tips

  • Enter only non-negative numbers to get a valid principal real fourth root.
  • If you need the fourth root of a negative number, consider using complex numbers or other methods.
  • Use this calculator to check your manual calculations or to speed up your work.

Common Mistakes to Avoid

  • Entering a negative number, which is not supported for principal real fourth root.
  • Confusing the fourth root with the square root; the fourth root is the square root of the square root.

Last updated: August 13, 2026