Calculate the Area and Circumference of a circle by entering the radius or diameter.
Input Type
Area:
Circumference:
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About Circle Calculations

The circle's area is calculated as π × r² and the circumference as 2 × π × r. You can enter either radius or diameter in different units.

How It Works

Choose the input type (radius or diameter), enter the value, and select the unit. Click calculate to see area and circumference instantly.

Advice

Always double-check units before using results in real-world projects. Use consistent units when performing further calculations.

FAQs

Can I enter diameter? Yes, select Diameter as input type.
Is π exact? This tool uses Math.PI which is accurate enough for general calculations.
Can I use inches or feet? Yes, select the desired unit from the dropdown.