Arc Length Calculator
Compute the length of a circular arc from the circle's radius and the central angle subtended by the arc. The calculator also reports the chord length and sector area for the same data.
Enter details
Enter radius and central angle, then press Calculate.
Arc length formulas
From degrees: L = (θ / 360°) · 2πr
From radians: L = rθ
Where r is the radius and θ is the central angle in the chosen unit.
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Frequently asked questions
The arc length equals the radius when the central angle is exactly 1 radian (≈ 57.2958°). That is the definition of a radian — the angle subtended by an arc equal in length to the radius.
Arc length is the distance along the curved edge of the circle. Chord length is the straight-line distance between the two endpoints of the arc — always shorter than the arc unless the angle is 0°.