Circle Calculator

Radius, diameter, circumference and area from any one of them, plus arc length, sector area, chord length and segment area.

Your result will appear here

Fill in the fields and press Calculate, or pick one of the examples.

About the Circle Calculator

Start from whichever measurement of a circle you know — radius, diameter, circumference or area — and get the other three.

Add a central angle to compute the arc length, sector area, chord length and the area of the circular segment cut off by the chord.

Example

radius 2, angle 90°

→ Area 12.566, arc length 3.1416

C = 2\pi r,\qquad A = \pi r^{2}

Circumference and area.

s = r\theta,\qquad A_{\text{sector}} = \tfrac{1}{2} r^{2}\theta

Arc length and sector area, with θ in radians.

\text{chord} = 2r\sin\tfrac{\theta}{2}

Chord subtending the angle θ.