Common Core Math Vocabulary

Perimeter - Definition with Examples

What is Perimeter?

Perimeter Definition: The perimeter is the total length of the sides or edges surrounding a shape

Perimeter = Sum of the lengths of all sides


Perimeter of Rectangle


Real Life Examples

A few practical applications of the perimeter in geometry include finding the length of the fence that covers a garden or finding the boundary of a soccer field or the length of a ribbon required to cover the borders of a table mat.

Perimeter Real life Examples


How to find the perimeter of a polygon?

Regular Polygon

The length of all sides of a regular polygon is equal. The perimeter of a regular polygon is determined by multiplying the number of sides by the length of any side.

Perimeter of a Regular Polygon  =  Number of sides  X  Length of a side


Perimeter of regular polygon


Non-Regular Polygon

The perimeter of non-regular shapes can also be calculated by adding the lengths of all the sides.

Perimeter of Non-Regular Polygon  =  Sum of the lengths of all sides


Perimeter of non regular polygon


The table below shows the perimeters of some common shapes.



P = a + b + c



P = 4 x a



P = 2 ( a + b )

Regular Pentagon

Regular pentagon

P = 5 x a

Regular Hexagon

Regular Hexagon

P = 6 x a

Regular Octagon

Regular octagon

P = 8 x a


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