Calculate radius, diameter, circumference, and area of a circle with exact π representations. Also solve circular sectors, arc lengths, chord lengths, and segment areas.
Radius is the distance from the center to any point on the perimeter.
The straight-line distance passing through the center connecting two boundary points.
Perimeter or distance around the circle.
The 2D surface enclosed by the circle boundary.
A circle is a shape consisting of all points in a plane that are at a given distance from a given center point. The ratio of circumference to diameter is always the mathematical constant π (pi ≈ 3.14159265).
Exact values retain the π symbol (e.g. 10π), while decimal approximations evaluate π ≈ 3.14159...
Multiply degrees by π / 180 to convert to radians: θ_rad = θ_deg × (π / 180).
Understanding your calculation
A circle with radius r has diameter 2r, circumference 2πr and area πr².
With radius 3, diameter is 6, circumference is approximately 18.850 and area is approximately 28.274 square units.
Confirm whether the input is radius or diameter. Circumference uses length units, while area uses square units.