# Circumference (Perimeter) of a Circle

LAST UPDATE: February 2nd, 2022

## Method #1 – Circumference from Radius

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

π is approximately 3.1415926535

Circumference = 2 x π x Radius

##### Example

A circle has a radius of 10

Circumference = 2 x π x 10 = 2 x 3.14159 x 10 = 62.83

## Method #2 – Circumference from Diameter

### Formula – How to calculate the circumference of a circle from the diameter

π is approximately 3.1415926535

Circumference = π x Diameter

##### Example

A circle has a diameter of 10

Circumference = π x 10 = 3.14159 x 10 = 31.4159

## Method #3 – Circumference from Area

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

π is approximately 3.1415926535

Circumference = 2 x √(π x Area)

##### Example

A circle has an area of 10

Circumference = 2 x √(π x 10) = 2 x √(3.14159 x 10) = 2 x √(31.4159) = 2 x 5.605 = 11.21