# Circumference of Circle Formula

## Formula

### Summary

The circumference of a circle is given by the constant (tau) multiplied by the radius of the circle, where and .

Variable Description
Circumference of the circle
The circle constant (tau), where
Note: This website uses the constant (tau) instead of (pi) as the default circle constant. The substitution can be used to translate between the two constants. See this page for the traditional circle area formula.

## Usage

The circumference of a circle is given by the constant (tau) multiplied by the radius of the circle. For example, to find the circumference of a circle with a radius of length 3 the formula is:

To calculate the circumference of a circle with a radius of length one, shown in the image above, multiply the circle constant (tau) by the value of the radius.

Steps
1. Set up the formula and substitute the value for into the formula.

2. Evaluate multiplied by .

3. The circumference of the circle is approximately 6.28318530718 units.

To calculate the circumference of a circle multiply the radius by the constant (tau) to get the result.

Steps
1. Set up the formula and substitute the value for into the formula.

2. Evaluate multiplied by .

3. The circumference of the circle is approximately 12.566 units.