Using the calculator
Enter the values requested above. Calculate circle area, circumference and diameter from radius.
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Circle Calculator
Calculate circle area, circumference and diameter from radius.
Enter the values for the problem
Enter the numbers, equation values, scores, or dimensions requested by the circle tool. Review the supporting outputs to check the result and understand the relationship between the values.
Important: Use the inputs that match your situation. Results are estimates based on the values and assumptions entered.
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How to use this calculator
Reading the result
The result shows the geometric value produced by the dimensions or coordinates entered. Supporting results provide the related measurements calculated from the same inputs.
How it is calculated
Circle calculations use the radius as the base measurement. Area is π times radius squared, circumference is 2π times radius, and diameter is twice the radius.
Results are estimates based on the values entered. Review the Methodology and Calculator Disclaimer for important limitations.