Circle Area
Circle area depends on the square of the distance from the centre to the boundary. It grows faster than the radius.
Circle Area
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.
A diameter is twice the radius. Entering diameter as radius makes the area four times too large.
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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The ratio of a circle's circumference to its diameter is constant, so division by pi reverses the measurement.
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