How circle calculator works
A circle is defined by its radius, the distance from the center to any point on the edge. From the radius, you can calculate three key properties: the area (the space inside), the circumference (the perimeter), and the diameter (the width across the center).
The formulas are: area = pi times radius squared, circumference = 2 times pi times radius, and diameter = 2 times radius. Pi is approximately 3.14159. This calculator applies these formulas using the full precision of JavaScript Math.PI.
Enter the radius and select what to calculate. Results are rounded to six decimal places. This is useful for geometry homework, engineering calculations, and any task involving circular shapes.