Circle Calculator

Calculate area, circumference, radius, and diameter from any known value

Input Values

Enter any one value to calculate the rest:

Radius

Diameter

Circumference

Area

cm²

Enter any value to see results

Circumference: C = 2πr = πd

Area: A = πr²

Diameter: d = 2r

Note: Calculations are provided as-is for educational and planning purposes. For critical applications, always verify results independently.

Calculate rectangular areas

Solve any triangle

Common shape areas

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