Calculators & Utilities

Circle Calculator

Calculate radius, diameter, circumference and area from any one circle measurement.

Free to use No account needed Quick result

Tool workspace

Private by design

Your result

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About the Circle Calculator

The Circle Calculator first derives radius from the selected known measurement, then computes diameter, circumference and area with JavaScript's full pi precision.

How to use the Circle Calculator

  1. Enter one positive circle measurement.
  2. Identify whether it is radius, diameter, circumference or area.
  3. Calculate all related measurements in the same units.

Practical tips

  • Area uses square units while the other outputs use linear units.
  • Keep extra precision until the final rounding step.
Helpful answers

Circle Calculator FAQs