Circle Calculator
Calculate radius, diameter, circumference, and area from any known value
What do you know?
Visual Reference
Circle dimensions (not to scale).
Formulas Used
- Diameter (d) = 2 × radius (r)
- Circumference (C) = 2 × π × r = π × d
- Area (A) = π × r²
Circle Properties
Radius (r)
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Diameter (d)
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Circumference (C)
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Area (A)
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π ≈ 3.14159265359
Enter any known value; all other properties will be calculated.
Circle Calculation Report
Input:
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Generated by Circle Calculator · Formulas: d=2r, C=2πr, A=πr²