How to Calculate the Diameter of a Circle From Its Circumference

A little math is required to determine the diameter of a circle from its circumference.

The diameter of a circle is the length of the circle, measured across the middle. Other ways to measure a circle include the radius, which is the distance from the midpoint of the circle to the outer edge, and the circumference, which is the distance around the outside edge of the circle. If you know one measurement of the circle, it is possible to determine the other measurements as well. With a simple mathematical equation you can determine the diameter of a circle if you already know the circumference.

Instructions

1. Write down the circumference of the circle.

2. Divide this number by Pi, which is 3.142.

3. The resulting number is the diameter of the circle.

References

• Math Open Reference: Diameter of a Circle
• Cool Math: The Geometry of Circles

Resources

• Additional Information on Circles and Pi from the University of Arkansas at Little Rock