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Understand the method before using any result. The details below describe the purpose and assumptions for this tool.
How the circle calculator works
The circle calculator helps you estimate results using the assumptions and values you provide. Review the formula and example before relying on the result.
Formula and assumptions
Circle area = πr²; circumference = 2πr.
Example
Enter the radius in your preferred unit.
Important information
Results depend on the values, jurisdiction, date and assumptions you enter. Financial products, tax rules and medical recommendations may vary by location and change over time. Verify critical results with reliable sources.