Write a Program to Calculate Area of Circle in Python

Calculating the area of a circle is a common geometry problem that can be solved in many programming languages, including Python. In this tutorial, we will learn how to write a program that calculates the area of a circle in Python.

To start, we need to understand the formula for calculating the area of a circle.

Table of Contents hide

1 Formula for Area of Circle

2 Algorithm for Area of Circle

2.1 Source Code

2.2 Output

3 Calculate Area of Circle Using Function

3.1 Source Code

3.2 Output

Formula for Area of Circle

The formula is: Area = π * r^2

where “Area” is the area of the circle.
“π” (pi) is a mathematical constant approximately equal to 3.14, and
“r” is the radius of the circle

Algorithm for Area of Circle

Here is a simple algorithm for calculating the area of a circle in Python:

Ask the user to input the radius of the circle.
Calculate the area of the circle using the formula:
area = pi * radius * radius.
Print the area of the circle.

From the above algorithm, we understood how to implement a python program to calculate the area of the circle. Now it is time to perform it practically.

But before writing this program you have to know about:

Source Code

import math

radius = float(input('Enter radius of the Circle: '))
area  = math.pi*(radius**2)

print(f"Area of Circle is {area}")

Output

Enter radius of the Circle: 2
Area of Circle is 12.566370614359172

Instead of writing math.pi you can directly write the value of pi that is 3.14

Now let’s write the same program by using function.

Calculate Area of Circle Using Function

But before writing this program few programming concepts you have to know:

Source Code

def circle_area(radius):
    area  = math.pi*(radius**2)
    return area

radius = float(input('Enter radius of the Circle: '))

Area = circle_area(radius)
print(f"Area of Circle is {Area}")