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Instant result
Enter the data and press the button to do the calculation.
Online Calculator
Circle Calculator
Enter the radius to find a circle’s main measurements.
Information
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Local processing
The values are processed directly in your browser.
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Free
No registration, external API or subscription required.
Frequently asked questions
What's the area of a circle?
A = πr².
How is the circumference calculated?
C = 2πr.
How is the diameter calculated?
d = 2r.
What units does it use?
The unit depends on the introduced radius; the area is expressed in square units.