CalculatorMath

Circle Area and Circumference Calculator

Calculate circle area and circumference from a positive radius. Radius 2 gives area 4π and circumference 4π. Area uses squared input units.

Instant · no account

Input

Enter your values

Radius

Method

How it works

Change any input above and the result updates instantly. The formula or method used by this tool is shown below.

Area = πr²; circumference = 2πr.

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Quick answers

About this tool

What does the Circle Area and Circumference Calculator do?+

Calculate circle area and circumference from a positive radius. Radius 2 gives area 4π and circumference 4π. Area uses squared input units.

How does this calculator calculate the result?+

It uses this method: Area = πr²; circumference = 2πr.

Are my inputs saved or sent to an account?+

Core CalcWorkspace tools require no account, and most calculations run locally in your browser. Favorites and recent-tool history, when used, stay in this browser.