How to Determine the Diameter of a Circle

By Rachel Pancare; Updated April 24, 2017

You can find the diameter of a circle by using other measurements of the circle. Before you begin calculating, be certain you understand the parts of a circle. The diameter is the distance across the circle from a point on one side to a point on the opposite side, passing through the exact middle point of the circle. You can use the radius, circumference or area to help you find this measurement.

Understanding the Parts of a Circle

Reviewing the parts of a circle gives you the foundation needed to make diameter calculations. and be certain you know the meaning of diameter. Remember, the diameter is a straight line segment that passes through the center of the circle. It is the longest chord of the circle -- a line segment that joins two points on a curve.

The radius measurement is the easiest measurement to use to find the diameter of a circle. The radius is half of the diameter. The circumference of a circle is the distance around the outer edge of the circle from one point, meeting back at that point. The area of a circle is the space inside the circle.