The perimeter of a shape is the total length of all of its sides.

 

Units of Perimeter

The units used for measuring perimeters are the units of length used for giving the dimensions of the shape.

Remember these units must be the same before you add them together.

The perimeter of a circle is called its circumference and is covered in Circles

 

Perimeter Formulae

Shape
Name
Perimeter
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Square

P= 4 × = 4l

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Rectangle

P = 2b + 2h

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Triangle

P = a + b + c

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Parallelogram

P = 2b + 2a

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Rhombus

P = Sum of all sides = 4b

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Trapezium

P = Sum of all sides