This calculator uses the radius of a circle to determine the diameter, circumference, and area of the circle. The formulas used to find these measurements are:
Diameter = 2 * radius
Circumference = 2 * radius * π
Area = π * r2
where π is the number “pi” and is equal to approximately 3.14159.
To find these measurements for a given circle, simply enter the radius of the circle below and then click the “Calculate” button.