Circle Calculator
Calculate circle properties: area, circumference, diameter, and sector area from the radius.
How to Use This Calculator
Enter your values in the fields above and click "Calculate" to get instant results. This circle calculator provides accurate results with step-by-step explanations.
Formula
A = πr² | C = 2πr | Sector = (θ/360)πr²
Quick Examples
- r=5 → Area ≈ 78.54, Circumference ≈ 31.42
- r=10 → Area ≈ 314.16
Frequently Asked Questions
How do I calculate the area of a circle?
Area = π × r², where r is the radius. For r=5, area = π × 25 ≈ 78.54 sq units.
What is a sector?
A sector is a "pie slice" of a circle. Its area is proportional to the angle: Sector Area = (angle/360) × πr².