# What Is a Circumference?

## What Is a Circumference?

The circumference is the distance measured around a circle.

The circumference is often denoted by C. The image below shows what we mean by the circumference: ### Dictionary Definition

The Oxford English Dictionary defines the circumference as "the curved line which forms the boundary of a circle."

## Examples of the Circumference

The circle below has a circumference of 20 cm. This is the distance around the circle. The circle below has a circumference of 12 inches. ## How to Find the Circumference

The circumference of a circle is related to its radius and diameter.

### How to Find the Circumference from the Radius

The circumference is the radius multiplied by 2π.

If the circumference is C and the radius is r (as shown in the image below), then we can find the circumference using the formula: Read more about how to find the circumference using the radius

### How to Find the Circumference from the Diameter

The circumference is the diameter multiplied by π.

If the circumference is C and the diameter is d (as shown in the image below), then we can find the circumference using the formula: Read more about how to find the circumference using the diameter

What is a circle? What is the radius? What is the diameter? Finding the circumference of a circle using the radius Finding the circumference of a circle using the diameter Learn about the circumference ( interactive widget)