Perimeter of a Square Calculator

Created by Hanna Pamuła, PhD candidate
Reviewed by Bogna Szyk
Last updated: May 26, 2021

This perimeter of a square calculator will help you with this basic calculation. Type the square side to obtain the perimeter, or use our tool the other way round: enter the perimeter to get the side length. If you're not sure what is a perimeter of a square or you've just forgotten the formula for the perimeter of a square, keep scrolling! You may also be interested in our square calculator which finds the square area and diagonal as well.

What is the perimeter of a square - formula

Image presenting perimeter of a square

Perimeter of a square is equal to sum of all square sides. Because square has all four sides equal in length, the perimeter is:

perimeter = a + a + a + a = 4 * a

A square is the quadrilateral of least perimeter enclosing a given area:

16 * area = perimeter² (because area = a² and perimeter² = (4 * a)² = 16 * a²)

For every other quadrilateral than square, the inequality occurs:

16 * area < perimeter²

Which means that a square has a larger area than any other quadrilateral with the same perimeter.

What is the perimeter of a 4 in square

The perimeter of such a square is calculated by adding all the sides together, or multiplying the side length by 4:

perimeter = 4 in + 4 in + 4 in + 4 in = 4 * 4 in = 16 in

Image explaining how to find the perimeter of a square

How to use the perimeter of a square calculator?

Let's have a look at an example. Imagine that you got a gift from your friend, a lovely oil painting, square-shaped. You would like to make a frame for it. However, you have no idea how long the pine board needs to be. Yes, you guessed right, you can use the perimeter of a square calculator!

  1. Measure the side of the square. For example, our painting's side is 3 ft 6 in. Change the unit by a simple click on its name and then type the value into the box.
  2. Perimeter of a square appears: it's 14 ft in our case. Of course, it's only an example, in real life you'll probably need more material as it depends on frame and board width and the way of joining frame corners.
Hanna Pamuła, PhD candidate
Image of a square with side a and diagonal d. Perimeter of a square
Side a
Diagonal d
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