Circle Area Calculator
Calculate the area of a circle using radius, diameter, or circumference. Formula: Area = π × r² where π (pi) ≈ 3.14159
Input Measurements
units
Quick Examples
Calculation Results
Area of Circle
314.16
square units
Step-by-Step Calculation
Circle Visualization
Circle Properties
Radius: 10 units
Diameter: 20 units
Area: 314.16 sq units
Circle Area Formulas
A = πr²
Area = π (pi) × radius squared
Using Diameter
A = π(d/2)²
If you know the diameter (d), divide by 2 to get radius, then square it and multiply by π
Using Circumference
A = C²/(4π)
If you know the circumference (C), square it, divide by 4π to get the area
π (Pi) Values
π ≈ 3.1415926535
Common approximations: 3.14 (simple), 3.1416 (standard), 22/7 (fraction)
