# How to Find the Circumference of a Circle ••• Spike Mafford/Photodisc/Getty Images

You can find the circumference of a circle by using the measurement of its diameter, radius or area. The circumference of a circle is the distance around the circle's edge from one point, meeting back at that point. Knowing how to calculate a circle's circumference can be useful in math class but also in real-life situations such as craft projects and construction tasks.

## Understanding the Circle

Reviewing the features of a circle before you begin is a good way to avoid calculating incorrectly. A circle is a symmetrical, round, two-dimensional figure. The circumference, or distance around the circle, includes a series of points that are all equidistant from the exact center of the circle. The diameter is a line segment that passes from one point on the circle's edge directly through the middle of the circle to a point on the circle's opposite edge. The radius is a line segment that extends from one point on the edge of the circle inward to the center of the circle. The area of a circle is the space inside the circle.

## Using the Diameter

The diameter is the simplest measurement for finding the circumference of a circle, and it requires the fewest steps. Start with the formula C = πd (circumference = 3.14 x diameter). If you enter π (pi) into your calculator, you will get the longer, more accurate value for pi. But you can also use the acceptable approximation for π, which is 3.14. If the diameter of a wheel is 10 inches, for example, your equation would read C = 3.14 x 10, which equals a circumference of 31.4 inches.