Circle Calc

Input radius, diameter, circumference, or area — calculate all others. Visual circle.

Any InputVisual Circle100% Private

Enter radius

Radius

5.000000

Diameter

10.000000

Circumference

31.415927

Area

78.539816

Formulas:

Circumference = 2 x pi x r

Area = pi x r squared

FAQ

What formulas are used?

Circumference = 2 x pi x radius. Area = pi x radius squared. Diameter = 2 x radius.

Can I input any measurement?

Yes. Enter radius, diameter, circumference, or area — the tool calculates all other values automatically.

What value of pi is used?

The tool uses the full JavaScript Math.PI constant (3.141592653589793) for maximum precision.

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