How To Calculate Area Of A Circle In Python

In this python tutorial, you will learn about how to calculate area of a circle in Python, you can check the Python program to calculate area of a circle and, also we will check:

Python program to calculate the area of a circle
Python program to find the area of a circle using function
Python program to find the area of a circle using the math module
Python program to calculate the area and circumference of a circle
Python program to calculate the area and circumference of a circle using an inbuilt math module
Python program to find the area and perimeter of a circle
Python program to calculate the area of a circle using class
Python program to calculate the area and perimeter of a circle using class

Table of Contents

Python program to calculate area of a circle

Let see python program to calculate the area of a circle.

Firstly, we will take input from the user using the input() function for radius and store it in a variable.
We can use constant to store the value of ‘pi’.
Now, we will calculate the area of a circle by using the formula area = PI * r * r.
And at last, print the area of a circle to get the output.

Example:

PI = 3.14
r = float(input("Enter the radius of a circle:"))
area = PI * r * r
print("Area of a circle = %.2f" %area)

You can refer to the below screenshot to see the output for python program to calculate the area of a circle

The above code, we can use to calculate area of a circle in Python.

Also, read, Python program to find an area of a rectangle and How to find area of a triangle in Python?

Python program to find area of a circle using function

Here, we will see python program to find the area of a circle using function.

In this example, I have defined a function as def findArea(r).
We can store the value PI = 3.14 which is fixed.
The function is returned as return PI * (r * r)
The function findArea(6) is called and it will print the output.

Example:

def findArea(r):
    PI = 3.14
    return PI * (r*r);
print("Area of circle = %.6f" % findArea(6));

You can refer to the below screenshot to see the output for the python program to find the area of a circle using the function.

Python program to find the area of a circle using function

The above python code to find area of a circle using function in Python.

Find area of a circle using Python math module

Now, we will see python program to find area of a circle using the math module.

In this example, we will import math module which is an inbuilt module.
We will take the radius as an input from the user.
Now, we will calculate the area of a circle by using the formula area = math.pi * r * r. The value of “pi” is taken from the “math” module.
And at last, print the area of a circle to get the output.

Example:

import math
r = float(input("Enter the radius of a circle:"))
area = math.pi * r * r
print("Area of a circle = %.2f" %area)

You can refer to the below screenshot to see the output for the python program to find the area of a circle using the math module.

The above code, we can use to find area of a circle using Python math module.

Also read, How to Create Countdown Timer using Python Tkinter.

Python program to calculate area and circumference of a circle

Let’s see python program to calculate the area and circumference of a circle.

Firstly, we will take input from the user using the input() function for radius and store it in a variable.
We can use constant to store the value of ‘pi’.
Now, we will calculate the area of a circle by using the formula area = PI * r * r.
And for calculating the circumference of a circle we will use the formula circumference = 2 * PI * r.
And at last, print the area and circumference of a circle to get the output. The value is formatted up to two decimal places using %.2f.

Example:

PI = 3.14
r = float(input(' Please Enter the radius of a circle: '))
area = PI * r * r
circumference = 2 * PI * r
print(" Area Of a Circle = %.2f" %area)
print(" Circumference Of a Circle = %.2f" %circumference)

You can refer to the below screenshot to see the output for the python program to calculate the area and circumference of a circle.

This is the Python program to calculate area and circumference of a circle.

Python program to calculate the area and circumference of a circle using an inbuilt math module

Here, we will see python program to calculate the area and circumference of a circle using an inbuilt math module.

Firstly, we will import math module which is an inbuilt module.
We will take input from the user using the input() function for radius and store it in a variable.
Now, we will calculate the area of a circle by using the formula area = math.pi * r * r.
And for calculating the circumference of a circle we will use the formula circumference = 2 * math.pi * r.
And at last, print the area and circumference of a circle to get the output. The value is formatted up to two decimal places using %.2f.

Example:

import math
r = float(input(' Please Enter the radius of a circle: '))
area = math.pi * r * r
circumference = 2 * math.pi * r
print(" Area Of a Circle = %.2f" %area)
print(" Circumference Of a Circle = %.2f" %circumference)

You can refer to the below screenshot to see the output for the python program to calculate the area and circumference of a circle using an inbuilt math module.

Python program to calculate the area and circumference of a circle using an inbuilt math module

Python program to find area and perimeter of a circle

Now, we will see python program to find the area and perimeter of a circle

Firstly, we will take input from the user using the input() function for radius and store it in a variable.
We have used 3.14 the value of pi in the formula.
Now, we will calculate the area of a circle by using the formula area = 3.14* r * r.
And for calculating the perimeter of a circle we will use the formula perimeter = 2*3.14*r
And at last, print the area and perimeter of a circle to get the output.

Example:

r=float(input("Enter the Radius of circle: "))
area = 3.14*r*r
perimeter = 2*3.14*r
print("Area of Circle: ",area)
print("Perimeter of Circle: ",perimeter)

You can refer to the below screenshot to see the output for the python program to find the area and perimeter of a circle.

The above code, we can use to find area and perimeter of a circle in Python.

Python program to calculate area of a circle using class

Let see python program to calculate the area of a circle using class.

In this example, we have created a class named “Circle” and it has an attribute radius as r.
The constructor of the class initiates the attribute using the __init__function.
We have used 3.14 the value of pi in the formula.
The method “area” is created to calculate the area of a given circle.
An instance of the class “Circle” is created as “obj” and the method is invoked to display the output.

Example:

class Circle:
    def __init__(self, r):
        self.radius = r
    def area(self):
        return 3.14 * (self.radius ** 2)
obj = Circle(8)
print("Area of circle:",obj.area())

You can refer to the below screenshot to see the output for the python program to calculate the area of a circle using class.

The above Python code is to calculate area of a circle using class.

Python program to calculate area and perimeter of a circle using class

Here, we will see python program to calculate the area and perimeter of a circle using class

In this example, we have created a class named “Circle” and it has an attribute radius as r.
The constructor of the class initiates the attribute using the __init__function.
We have used 3.14 the value of pi in the formula.
The two methods “area” and “perimeter” are created to calculate the area of a given circle.
An instance of the class “Circle” is created as “obj” and the method is invoked to display the output.

Example:

class Circle:
    def __init__(self, r):
        self.radius = r
    def area(self):
        return 3.14 * (self.radius ** 2)
    def perimeter(self):
        return 2*3.14*self.radius
obj = Circle(3)
print("Area of circle:",obj.area())
print("Perimeter of circle:",obj.perimeter())

You can refer to the below screenshot to see the output for the python program to calculate the area and perimeter of a circle using class.

You may like the following Python tutorials:

In this Python tutorial, we have learned about the Python programs to calculate the area of a circle. Also, we covered these below topics:

How to calculate the area of a circle in Python
How to find the area of a circle using a function in Python
How to find the area of a circle using the math module in Python.
How to calculate the area and circumference of a circle in Python.
Python program to calculate the area and circumference of a circle using an inbuilt math module
How to find the area and perimeter of a circle in Python
How to calculate the area of a circle using class in Python
How to calculate the area and perimeter of a circle using class in Python.

Bijay Kumar

I am Bijay Kumar, a Microsoft MVP in SharePoint. Apart from SharePoint, I started working on Python, Machine learning, and artificial intelligence for the last 5 years. During this time I got expertise in various Python libraries also like Tkinter, Pandas, NumPy, Turtle, Django, Matplotlib, Tensorflow, Scipy, Scikit-Learn, etc… for various clients in the United States, Canada, the United Kingdom, Australia, New Zealand, etc. Check out my profile.

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