How to calculate the perimeter of a rectangle

To remove the perimeter of a geometric figure consists in adding the length of all the sides that form it; It is not a complicated operation, but it is always much easier if we have a mathematical formula to apply. That is why in this article we want to explain in detail the steps to follow so that you can learn how to calculate the perimeter of a rectangle.

Steps to follow:


The perimeter corresponds to the sum of the lengths of all the sides of the geometric figure in question. In the case of the rectangle, it will consist of adding both bases and both heights:

P = a + b + a + b

Thus, we can group their sides in pairs, since they are equal and the formula to be applied will be:

P = 2a + 2b


Let's give a practical example to understand more easily how the perimeter of a rectangle is calculated ; suppose that the rectangle has a base of 11 cm and its height measures 7 cm, it removes its perimeter.

The first thing we will do is replace the values ​​in the formula to calculate the perimeter:

P = 2x7 + 2x11


Next, you must do the calculation remembering the order of priority of mathematical operations that indicates that the multiplications must be made before the additions, so that:

P = 14 + 22 = 36 cm

And so we get that the perimeter of a rectangle is 36 cm.


In case we wanted to take out the area of ​​the rectangle, the formula would be different:

A = b · a

And if we continue with the previous example, we would obtain that:

A = 11 x 6 = 66 cm²

Remember that the area should always be expressed in cubic measures, so in this specific case we would have that the area corresponds to 66 cm².


To learn to look for the perimeter of other figures, we recommend our articles:

  • How to find the perimeter of a square
  • How to calculate the circumference of a circumference
  • How to calculate the perimeter of a triangle