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Sector Calculator
Enter radius and angle — sector area and arc length update instantly.
Formula
Area = (θ/360)·πr² | Arc length = (θ/360)·2πr (θ in degrees)
Example
r = 100 mm, θ = 90° → Area = 7854 mm², arc = 157.08 mm (exactly a quarter circle).
FAQ
How is a sector area calculated?
Sector area is the fraction θ/360 of the full circle area. For θ in radians: Area = ½·r²·θ.
What is the difference between arc length and chord length?
Arc length follows the curve; the chord is the straight line between the endpoints. They are equal only for tiny angles.