Circle Area Calculator
Compute the area of a circle from its radius.
Input Data
Radius
Results
Area = πr².
78.54
Explanatory note about the result.
面積 = π·r² = π·5² = 78.54。
At a glance:Area = π·r². Complements circle-circumference and circle.
Formula
Area = π·r².
How to Use
- Enter the radius.
- The tool returns the area.
Case Studies
r=3
Area = π·9 ≈ 28.27.
FAQ
Area vs circumference?
Area is the enclosed region (πr²); circumference is the boundary (2πr).
Related Tools
References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.