Square Root Calculator

Calculate the principal square root of any nonnegative number with a precise decimal result.

Find a square root
Enter zero or a positive integer or decimal.

About square roots

The square root of a nonnegative number is a value that produces the original number when multiplied by itself. This square root calculator finds the principal, or nonnegative, square root and displays a precise decimal answer. It works with whole numbers and decimals and identifies when an integer input is a perfect square. Students can use it to check arithmetic, while professionals can use it for geometry, engineering, statistics, finance, and any formula involving a squared quantity. For example, the square root of 144 is 12 because 12 multiplied by 12 equals 144. The number 144 is called a perfect square because its principal square root is an integer. The square root of 2 is not an integer or a terminating decimal. It is an irrational number whose decimal digits continue without repeating, so the calculator shows a rounded approximation. Calculations retain the available floating-point precision before the display is rounded. Every positive number technically has two values that solve an equation of the form x squared equals n: one positive and one negative. For 25, both 5 and negative 5 square to 25. However, the square root symbol conventionally means the principal nonnegative root, so the calculator returns 5. When solving equations, remember to consider both positive and negative solutions if the context requires them. Zero is a special case whose square root is exactly zero. Negative real numbers do not have real square roots because multiplying two real numbers with the same sign always gives a nonnegative product. Complex mathematics defines the imaginary unit as the square root of negative one, allowing roots of negative values to be expressed with imaginary numbers. This calculator focuses on real square roots and therefore asks for a value greater than or equal to zero. Square roots reverse squaring and appear throughout mathematics. The Pythagorean theorem uses a square root to convert a sum of squared lengths into a distance. Standard deviation takes the square root of variance so the result returns to the original unit. Area formulas use square roots to recover a side length from a square area. Roots also appear in quadratic formulas, growth models, electrical calculations, and computer graphics. To verify any displayed result, multiply it by itself and compare the product with the original input; the calculator includes that check directly beneath the answer.

Square root examples

Perfect squares have integer roots, while other values may have decimal approximations.

NumberPrincipal square rootClassification
14412A perfect square.
21.4142135624An irrational root shown as a decimal.
0.250.5A decimal with an exact root.
00Zero is its own square root.

How to use the square root calculator

  1. Enter the nonnegative number whose square root you need.
  2. Select Calculate square root.
  3. Read the principal root and its perfect-square classification.
  4. Review the multiplication check to confirm the result.

Square root calculator FAQ

What is a principal square root?

It is the nonnegative value represented by the square root symbol. Although positive numbers have positive and negative equation solutions, the principal root is never negative.

What is a perfect square?

A perfect square is an integer that equals another integer multiplied by itself. Examples include 0, 1, 4, 9, 16, and 25.

Can I calculate the square root of a decimal?

Yes, enter any finite decimal greater than or equal to zero. Some decimal roots are exact and others are displayed as rounded approximations.

Why are negative inputs not accepted?

Negative numbers have no square root within the real number system. Their roots require imaginary or complex notation, which this calculator does not cover.

How can I check a square root answer?

Multiply the displayed root by itself. The product should equal the original number, apart from a tiny difference caused by decimal rounding.