C# is a general-purpose, modern and object-oriented programming language pronounced as “C Sharp”. In this article, we will see how to calculate the area of a circle in C#.
The area of a circle can be evaluated using the formula:
Area of circle = pi * r * r //where r is the radius of circle
Example 1:
// Program to implement area of circle in C#
using System;
class Circle
{
static void Main(string[] args)
{
Console.Write("Enter Radius: ");
double rad = Convert.ToDouble(Console.ReadLine());
double area = Math.PI * rad * rad;
Console.WriteLine("Area of circle is: " + area);
}
}
Output:

Code Explanation:
The formula used to calculate the circle area: π * r * r. Where, r is the radius and π is the mathematical constant Pi. We will take the value of radius from the user as input. For π, we can either define a variable and assign it up to a specific decimal place or we can use Math.PI constant that is available in C#.
- The Radius is a double value to keep the radius of the circle.
- The area is double to save the area of the circle.
- The final area is stored in the double area.
- Finally, we are writing down the area of a circle.