How to Find the Perimeter of a Rectangle?

The perimeter P of a rectangle is given by the formula

P = 2 L + 2 W


where L and W are the length and width, respectively, of the of the rectangle.

How to Find the Perimeter of a Rectangle? Examples with Solutions

Example 1
Find the perimeter of a rectangle of length 20 meters and width 10 meters.
Solution to Example 1
Both the length L and the width W have the same units. We need to substitute L and W by their values in the formula of the perimeter as follows
P = 2 L + 2 W = 220 + 210 = 40 + 20 = 60 meters


Example 2
The length of a rectangle is 12.5 meters and its width is 800 centimeters. Find the perimeter of the rectangle in centimeters.
Solution to Example 2
Since we need to find the perimeter in centimeters, we first need to convert the length in centimeters.
L = 12.5 meters = 12.5 100 = 1250 centimeters
The perimeter P of the rectangle is given by
P = 2 L + 2 W = 2 1250 + 2 800 = 4100 centimeters


Example 3
The length of a rectangle is 240 meters and its width is the third of its length. Find the perimeter of this rectangle.
Solution to Example 3
We first need to find width W of the rectangle given its length L = 240 meters.
W = (1/3) L = (1/3) 240 = 1 240 / 3 = 80 meters
The perimeter P of the rectangle is given by
P = 2 L + 2 W = 2 240 + 2 80 = 640 meters


Example 4
The width of a rectangle is 1200 meters and its length is 500 meters longer that its width. Find the perimeter of this rectangle.
Solution to Example 4
We first need to find length L of the rectangle given its width W = 1200 meters.
L = 500 + W = 500 + 1200 = 1700 meters
The perimeter P of the rectangle is calculated as follows
P = 2 L + 2 W = 2 1700 + 2 1200 = 5800 meters

Example 5
A large rectangular field of length 500 meters and width 400 meters is to be enclosed along its perimeter by a fence. What is the total cost of the fence if the rate is $2 per meter?
Solution to Example 5
We need to find the perimeter
P = 2 L + 2 W = 2500 + 2400 = 1000 + 800 = 1800 meters
Every meter costs $2 to fence. Hence the total C cost to fence this field is given by
C = P 2 = 1800 2 = $3600

More References and links

Perimeter Questions With Answers and Solutions
Area, Perimeter and Diagonal of a Rectangle - Calculator .
Length and Width of Rectangle - Geometry Calculator.