Enter any one measurement (radius, diameter, circumference, or area) to calculate all other properties of a circle.
Enter one value — all others will be calculated automatically.
Arc & Sector
| Property | Value |
|---|
| Property | Formula |
|---|---|
| Diameter | d = 2r |
| Circumference | C = 2πr = πd |
| Area | A = πr² |
| Arc length | L = rθ (θ in radians) = (θ/360)×2πr |
| Sector area | A = ½r²θ = (θ/360)×πr² |
| Chord length | c = 2r×sin(θ/2) |
π ≈ 3.14159265358979… It is an irrational number, meaning its decimal expansion never repeats or terminates. The ratio of a circle's circumference to its diameter is always exactly π, regardless of the circle's size.