About the circle sector & arc calculator
A sector is a “pie slice” of a circle bounded by two radii and an arc. With the central angle θ in radians, the arc length is simply rθ and the area is r²θ/2. Angles here can be entered in degrees or radians (toggle above) and go all the way to 360°.
Given a chord and radius, there are two sectors, the minor and major one, and both are shown.
Formulas
| Arc length | s = rθ (θ in radians) |
| Sector area | K = r²θ/2 = rs/2 |
| Chord | c = 2r·sin(θ/2) |
Frequently asked questions
How do I calculate arc length?
s = r·θ with θ in radians, or s = 2πr·(θ°/360°) with θ in degrees.
How do I find the area of a sector?
K = ½r²θ (radians) or πr²·(θ°/360°).