Circle Area Calculator
Calculate circle area, circumference, diameter, and radius
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Formula
Formula
Area = πr²; Circumference = 2πr; Diameter = 2r; Radius = d/2 = C/2π = √(A/π)
All circle properties are interrelated through π. Knowing any one value allows calculating all others.
How to Calculate Manually
- 1 Select which value you know (radius, diameter, circumference, or area)
- 2 Enter that value
- 3 Calculator computes radius first
- 4 Then derives all other properties
- 5 Shows all four measurements
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Reference Table
| Radius | Diameter | Circumference | Area |
|---|---|---|---|
| 1 | 2 | 6.283 | 3.142 |
| 2 | 4 | 12.566 | 12.566 |
| 5 | 10 | 31.416 | 78.540 |
| 10 | 20 | 62.832 | 314.159 |
The circle is one of the most fundamental shapes in geometry. Its properties - radius, diameter, circumference, and area - are all interconnected through the mathematical constant π (pi). Understanding these relationships...
Frequently Asked Questions
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What is the formula for circle area?
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What is the formula for circumference?
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How do I find radius from area?
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