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Python Program to Find the Area and Perimeter of a Rectangle

Beginner · Basics

The area of a rectangle is the space inside it, length x width, and the perimeter is the distance all the way round it, 2 x (length + width). This program works out both for a rectangle with given sides.

Program

area_and_perimeter_of_rectangle.py
length = 12 # in m; or: length = float(input("Enter the length: "))
width = 8 # in m; or: width = float(input("Enter the width: "))
area = length * width
perimeter = 2 * (length + width)
print("Length:", length, "m")
print("Width:", width, "m")
print("Area:", area, "square m")
print("Perimeter:", perimeter, "m")
if length == width:
print("All sides are equal, so this rectangle is a square")
Output
Length: 12 m
Width: 8 m
Area: 96 square m
Perimeter: 40 m

How it works

  1. length * width gives the area, measured in square units because two lengths are multiplied.
  2. 2 * (length + width) gives the perimeter, since a rectangle has two lengths and two widths.
  3. The brackets matter: 2 * length + width would add only one width.
  4. The last check spots a square, the special rectangle whose length equals its width.

Other ways to write it

With the diagonal

With the diagonal
import math
length, width = 12, 5
diagonal = math.sqrt(length ** 2 + width ** 2) # Pythagoras
print("Area:", length * width)
print("Perimeter:", 2 * (length + width))
print("Diagonal:", diagonal)
Output
Area: 60
Perimeter: 34
Diagonal: 13.0

The diagonal splits the rectangle into two right-angled triangles, so Pythagoras gives its length: 13 for a 12 by 5 rectangle.

A function that returns two values

A function that returns two values
def rectangle(length, width):
return length * width, 2 * (length + width)
for l, w in [(12, 8), (5, 5), (7.5, 2)]:
area, perimeter = rectangle(l, w)
print(f"{l} x {w}: area = {area}, perimeter = {perimeter}")
Output
12 x 8: area = 96, perimeter = 40
5 x 5: area = 25, perimeter = 20
7.5 x 2: area = 15.0, perimeter = 19.0

A Python function can return two values at once, and area, perimeter = ... unpacks them into two variables.

Try it yourself

Work out the cost of fencing the rectangle at Rs 150 per meter of perimeter.

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