A circle's full circumference is 2πr, but real life rarely hands you a whole circle — it hands you a slice: the curved edge of a pie slice, the bend in a pipe, the arc of a rainbow you are trying to measure. Arc length is the distance along that curve, and the formula is beautifully compact: s = rθ, where r is the radius and θ is the central angle in radians. The radian requirement is the tripwire — if your angle is in degrees, convert first by multiplying by π/180, because s = rθ only works in radians. A 60° slice of a circle with radius 5 has an arc length of about 5.24 units (5 × π/3). Machinists sizing curved cuts, landscapers laying out circular beds, and runners on a track's curved sections all compute arc lengths. This calculator does the arithmetic: enter your values in the Variable A and Variable B fields and read the Result. Just keep the units consistent — radius in feet gives arc length in feet — and double-check that degree-to-radian conversion.

With the pre-filled defaults — Variable A 10, Variable B 5 — the Arc Length Calculator returns Result 50.0000. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.