Want to calculate the diameter of a circle? Cool, try this calculator.

About This Calculator

This diameter of a circle calculator will figure out the diameter of any circle given the circumference, the radius, or the area of the circle.

Terminology

"Area" - The amount of surface covered by a two dimensional shape. It is expressed in square units of measurement, for example square feet, square meters, square inches, square yards, etc.

"Circumference" - The total distance around the outside edge of a circle.

"Diameter" - The distance of a straight line that extends from edge to edge of the circle while passing through the center of the circle.

"Radius" - The distance of a straight line that extends from the center of the circle to the edge of the circle.

Calculating the Diameter of a Circle Using Circumference

If you know the circumference of a circle, you can calculate the diameter based on the following formula:

d = C / ϖ

where

C = Circumference
ϖ = Pi = 3.14159265...
d = Diameter

Calculating the Diameter of a Circle Using Radius

If you know the radius of a circle, you can calculate the diameter based on the following formula. This one's easy, the diameter is always double the radius:

d = 2 r

where

r = Radius
d = Diameter

Calculating the Diameter of a Circle Using Area

If you know the area of a circle, you can calculate the diameter based on the following formula: