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Circle Area Calculator
Calculate area and circumference of a circle
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Math & Geometry ✅ Free to Use
Circle Area Calculator
Calculate area, circumference, diameter, and radius of a circle. Enter any known measurement and get all other properties instantly.
5.000
Radius
10.000
Diameter
78.540
Area
31.416
Circumference
Circle Properties
Radius (r): 5.000000 units
Diameter (d): 10.000000 units
Area (A): 78.539816 units²
Circumference (C): 31.415927 units
Area Formula: A = πr²
Circumference Formula: C = 2πr
Diameter Formula: d = 2r
π (Pi) Value: 3.141593
Sector Calculations
Calculate area and arc length for different sector angles
30°
Area: 6.54
Arc: 2.62
45°
Area: 9.82
Arc: 3.93
60°
Area: 13.09
Arc: 5.24
90°
Area: 19.63
Arc: 7.85
120°
Area: 26.18
Arc: 10.47
180°
Area: 39.27
Arc: 15.71
270°
Area: 58.90
Arc: 23.56
360°
Area: 78.54
Arc: 31.42
Circle Visualization
Circle (Circumference)
Radius
Diameter
Circle Formulas & Tips
📐 Key Formulas
• Area: A = πr² = π(d/2)²
• Circumference: C = 2πr = πd
• Diameter: d = 2r
• Radius: r = d/2 = C/(2π)
💡 Practical Applications
• Calculate pizza or cake area
• Determine garden bed size
• Find wheel circumference
• Calculate pipe cross-section