Circle Circumference
The circumference is the length around a circle. The constant ratio between circumference and diameter is pi.
Circle Circumference
Circles · 1 input
How to use this calculator
- Enter radius in cm.
- Select Calculate and keep the output unit with the answer.
Before you use the answer
Start with a dimensioned sketch and label the units beside every measurement. Distinguish the outer edge from an internal opening, and distinguish a radius from a diameter. A geometric model is most useful when the shape actually matches the assumptions in the formula.
Keep radius and diameter distinct. Circumference uses linear rather than square units.
Does it save my inputs?
No calculation history is stored by this website. The calculator works locally in your browser. See the privacy policy for hosting and contact details.
Why might a result be approximate?
Measurement uncertainty, ideal-model assumptions and floating-point rounding can all matter. Displaying more digits does not improve the original measurement.
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