# Area of a Circle

LAST UPDATE: February 2nd, 2022

## Method #1 – Area from Radius

### Formula – How to calculate the area of a circle using the radius

π is approximately 3.1415926535

##### Example

A circle has a radius of 10

Area = π x 102 = 3.14159 x 102 = 3.14159 x 100 = 314.59

## Formula – How to calculate the area of a circle using the diameter

π is approximately 3.1415926535

Area = 2 x π x Radius2

##### Example

A circle has a diameter of 10

Area = 2 x π x 102 = 2 x 3.14159 x 102 = 2 x 3.14159 x 100 = 628.318

## Method #3 – Area from Circumference

### Formula – How to calculate the area of a circle using the circumference

π is approximately 3.1415926535

Area = π x (Circumference ÷ π ÷ 2)2

##### Example

A circle has a circumference of 10

Area = π x (10 ÷ π ÷ 2)2

Area = 3.14159 x (10 ÷ 3.14159 ÷ 2)2

Area = 3.14159 x (1.59155)2

Area = 3.14159 x 2.5330

Area = 7.5976