Square Root Calculator to Find Square Root of a Number

Square Root Calculator Sign

This calculator will calculate the square root of a number and indicate whether or not the radicand is a perfect square.

Plus, unlike other sites with a radicand calculator, if the radicand is not a perfect square, this calculator will calculate the nearest perfect squares that are greater and less than the entered radicand.

If you would like to find the square (or any other power) of a number, please visit the Exponent Calculator.

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Square Root Calculator

Calculate the square root of a number and find out whether or not the number is a perfect square.

Special Instructions

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Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None


Enter the radicand (the number you are trying to find the square root of), which can be any number greater than or equal to zero. The radicand is the number inside the radical sign (√), whereas the index is located to the left and above the radical sign. If you wish to find the square root of a fraction, enter the fraction into the mini conversion calculator, and I will convert it to a decimal and enter it into the radicand field for you.

Convert Fraction to Decimal
Square roots:Square roots:Square roots:Square roots:

Square roots:

This is the result of the square root calculation. If the result is a lengthy decimal number, the result is most likely an approximation. In any case, the result always represents two square roots (one positive and one negative).

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

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Help and Tools


Square roots and perfect squares.

What are Square Roots?

Definition of a square root: The opposite of squaring a number. For example, finding the square root of 81 is the same as asking, "what number, when squared, is equal to 81?"

Of course, if you know that 9 x 9 = 81, you will know that the square root of 81 is 9 (92 = 81). However, what you might not realize is that -9 is also a square root of 81, because -9 x -9 also equals 81.

In other words, all numbers greater than zero (zero can never be negative or positive) have two square roots -- one positive and one negative. This is why when using an online square root calculator, the result will always be preceded by a ± sign.

As for negative numbers, since a negative times a negative always yields a positive number, negative numbers cannot have a real value square root.

What Are Perfect Squares?

When a number has a square root that is a whole number, that number is said to be a perfect square. For example, since √4 has a square root of 2, 4 is said to be a perfect square. Here is a list of the perfect squares up to 225:

List of Perfect Squares up to 225


If you are still having a hard time understanding square roots, please let me know in the feedback form located beneath the calculator, and I will try to improve my explanations on this page.

Can I get a "root! root!"? :-)

Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.