Work out chain drive length instantly with clear inputs, formula shown and shareable results.
Chain length in pitches is 2C/p + (N1 + N2)/2 + [(N2 - N1)/(2 pi)]² / (C/p). The result is always rounded up to an even number of pitches so the chain can be joined with a standard connecting link rather than an offset link, which is weaker.
Chain length
L pitches = 2C/p + (N1 + N2)/2 + [(N2 - N1)/(2 pi)]² / (C/p)
L pitches = 2C/p + (N1 + N2)/2 + [(N2 - N1)/(2 pi)]² / (C/p). Chain length in pitches is 2C/p + (N1 + N2)/2 + [(N2 - N1)/(2 pi)]² / (C/p).
An odd length needs an offset or half link, which is the weakest element in the chain and the usual failure point on a shock-loaded drive.
This calculator takes 4 inputs: Small sprocket teeth, Large sprocket teeth, Centre distance, Chain pitch. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.