Calculate the side of a square

Do you need calculate the side of a square? Below you will find all the ways to get how long one of the sides of this four-sided figure is and if there is any other method, let us know and we will add it.

Many geometry problems ask us to calculating the side of a square from its diagonalso you can use our calculator and get the result automatically. For the rest of the cases we will explain it theoretically.

How to calculate the side of a square by knowing the diagonal


If we are asked to calculate the side from the diagonal of a squarethe procedure to follow is based on the Theorem of Pythagoras. If you want to know more about this theorem, visit the link we just left you.

If we adapt the Pythagorean Theorem to a square having all sides equalwe are left with the following formula:

d2 = a2 + a2 = 2a2

Esa fórmula básicamente nos dice que la diagonal del cuadrado elevada al cuadrado es igual al doble del lado del cuadrado al cuadrado. Ahora lo que tenemos que hacer es despejar de ahí la incógnita 'a' que es la que nos interesa para calculating the side of the square from the diagonal:

a = diagonal/√2

To better understand the procedure, let's see it with a solved example.

Calculate the side of a square whose diagonal is 12

They give us a square whose diagonal measures 12 centimeters and we are asked to find how long its sides are. To do this, we use the formula seen in the previous point and we have that:

a = 12 cm / √2 = 8,48528 cm

If we want to check that the value we have obtained is correct, it is enough to resort to the Pythagorean Theorem and check that the initial formula is fulfilled:

d2 = 12 x 12 = 144

2a2= 2 x 8.48528 x 8.48528 = 144

As you can see, equality holds, so that we have calculated the sides of the square correctly. If the equality is not met by tenths or hundredths, you may be carrying over inaccuracies as a result of rounding.

How to calculate the side of a square having the area

The formula of the area of a square tells us that we must multiply side by side, that is:

Area of a square = side2

So for calculate the side of a square from its area we simply have to make the square root of its surface:

Side of square = √(area of square).

For example, if we are given a square with a surface area of 100cm2how long is its side?

l = √100 = 10 cm

It's easy, isn't it?

Calculate the side of a square inscribed in a circle

Square inscribed in a circle

If we have a square inscribed in a circle of radius rwe can calculate the side with the following formula:

side = √2r2

For example, if we are given a square inscribed in a circle of 6 cm radius, how long is its side? To solve it we apply the above formula and we have that:

side = √2r2 = √(2 x 6 x 6 x 6) = √72 = 8,485 cm

If you have any doubts about how to calculate the side of a square using the methods described above or any other method not listed here, write us a comment and we will help you solve your questions.

Leave a Comment

Information on data protection

  • Responsible: Ignacio Cuesta
  • Purpose of processing: Spam control, comment management, etc.
  • Legitimation: Your consent
  • Communication of data: Data will not be communicated to third parties except by legal obligation.
  • Rights: Access, rectification, portability, forgetfulness.
  • Contact us:
  • Additional information: More information at our privacy policy.