Sector Area Calculator
Compute the area, arc length, chord length and perimeter of a circle sector (the "pie slice" shape) from the radius and central angle. Angles can be entered in degrees or radians.
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Enter radius and central angle, then press Calculate.
Sector formulas
Area: A = (θ / 360°) · πr² (degrees) or A = ½ r²θ (radians)
Arc length: L = (θ / 360°) · 2πr (degrees) or L = rθ (radians)
Chord: c = 2r · sin(θ / 2)
Perimeter: P = L + 2r
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Frequently asked questions
A sector is the portion of a circle bounded by two radii and the arc between them. It looks like a slice of pie. The central angle is the angle between the two radii.
Yes. Angles up to 360° are valid. An angle greater than 180° describes a "major sector" that covers more than half the circle. The chord formula still gives a straight-line distance between the two radius endpoints.