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.

## 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:

- math module (Optional)
- how to take user input in python
- Python operators

### 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

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

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:

- math module (Optional)
- how to take user input in python
- Python operators
- Python Functions

### 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}")
```

### Output

Enter radius of the Circle: 7 Area of Circle is 153.93804002589985 |