Quickly compute the area of any circle using our powerful, easy-to-use calculator. Perfect for students and pros needing instant, stress-free results.
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The area of a circle is the space enclosed within its boundary. It's a foundational concept in geometry and widely used in engineering, construction, and science.
A = πr²Where:
If you have the diameter (d) instead of the radius, use:
A = π(d/2)² = πd²/4A = ∫₀²π ∫₀ʳ r dr dθ = πr²This double integral in polar coordinates confirms the standard area formula.
Get started now and calculate your circle’s area with total confidence!
| Input | Formula Used | Result |
|---|---|---|
| Radius = 5 cm | A = π * 5² | 78.54 cm² |
| Diameter = 10 cm | A = π * (10/2)² | 78.54 cm² |
| Radius = 0 | A = π * 0² | 0 cm² (edge case) |
| Negative radius = -3 | Invalid input | Error: Radius cannot be negative |
| Very large radius = 106 m | A = π * (106)² | 3.14 × 1012 m² |