Circle Calculator

From radius, diameter, circumference or area — get all circle measurements at once.

Known value:

Value:

How to use

Pick your known value, enter it and click Calculate. Everything runs in your browser — nothing is uploaded or stored.

How do I get the area from the diameter?

Pick “Diameter” and enter it — area is computed for you.

Which value should I start from?

Whichever you measured; the rest are derived.

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Every tool runs 100% in your browser — no uploads, no signups. If a tool saved you time, consider supporting us with a small donation.