Trigonometry · Released

Arc and Chord Calculator

Solve circular arc geometry from any two known values: radius, central angle, chord length, arc length, or sagitta (bow height). Used for arc milling, radius gauges, cam profiles, and template layout.

Radius R — mm

Central angle θ — degrees

Chord length C — mm

Arc length L — mm

Sagitta h (bow height) — mm

Radius R

—

Central angle θ

—

Chord length C

—

Arc length L

—

Sagitta h

—

Formula and use

Chord: C = 2R·sin(θ/2)

Arc length: L = R·θ (θ in radians)

Sagitta: h = R·(1 − cos(θ/2))

Enter any two known values and the calculator solves the other three. All lengths in mm, angles in degrees.

Common uses: checking arc milling programs, laying out curved brackets, setting up radius gauges, and converting between chord/arc/sagitta measurements on a part drawing.