What does the square root calculator do?

It computes the principal (non-negative) square root of any non-negative number and tells you whether the input is a perfect square.

What formula does it use?

The square root of n is the non-negative real number r such that r × r = n. The tool computes this using IEEE-754 double-precision arithmetic.

What happens if I enter a negative number?

The tool returns an error. The square root of a negative number is not a real number — it would be an imaginary number, which this calculator does not output.

How accurate is the result?

For perfect squares the result is exact. For other numbers the result is correct to about 15–16 significant digits, displayed up to 10 decimal places.

Does this tool store my numbers?

No. The calculation runs entirely in your browser; nothing is sent to a server or saved between visits.

Is the square root calculator free?

Yes. It is free to use with no signup, no account, and no usage limit.

Square Root Calculator

Compute √n for any non-negative number, with perfect-square detection.

Written by Golam Rabbani, Founder & Lead Engineer

This interactive tool requires JavaScript. Read the formula and worked example below; you can compute the result by hand.

How to use this square root calculator

Enter a non-negative number in the Number field.
Press Calculate to see the square root.
Read whether the input is a perfect square in the explanatory line.
Use Copy to put the result on your clipboard, or Reset to clear the input.

About this square root calculator

The square root calculator returns the principal (non-negative) square root of any number greater than or equal to zero. The result is shown to up to ten decimal places, and the tool also flags whether the input is a perfect square — that is, whether the result is a whole integer.

The square root of n is defined as the non-negative real number r such that r × r = n. For perfect squares like 144, the result is exact: √144 = 12 because 12 × 12 = 144. For non-perfect squares like 2, the result is irrational and is shown as a decimal approximation: √2 ≈ 1.4142135624. The calculator uses JavaScript's built-in Math.sqrt under the hood, which is accurate to standard IEEE-754 double precision (about 15–16 significant digits).

Use cases include geometry (finding side lengths from area), physics (root-mean-square values), statistics (standard deviation from variance), and any place the inverse of squaring is needed.

FAQ

What does the square root calculator do?: It computes the principal (non-negative) square root of any non-negative number and tells you whether the input is a perfect square.
What formula does it use?: The square root of n is the non-negative real number r such that r × r = n. The tool computes this using IEEE-754 double-precision arithmetic.
What happens if I enter a negative number?: The tool returns an error. The square root of a negative number is not a real number — it would be an imaginary number, which this calculator does not output.
How accurate is the result?: For perfect squares the result is exact. For other numbers the result is correct to about 15–16 significant digits, displayed up to 10 decimal places.
Does this tool store my numbers?: No. The calculation runs entirely in your browser; nothing is sent to a server or saved between visits.
Is the square root calculator free?: Yes. It is free to use with no signup, no account, and no usage limit.