Piñonario Power transmission toolsES
Roller chain drives

Chain length calculator

From the pitch, the teeth on each sprocket and the center distance: how many links to buy, where the shafts end up and whether the design is sound.

Drive data

Chain, teeth on each sprocket and center distance.

1 Chain
Units
C

106 links · ANSI 40

N17 → N34 · 1/2" x 5/16"

Chain

in
Links (pitches)
106
Chain length
53.000
Exact theoretical length
105.68 pitches

Rounded up to the next even number so a standard connecting link can be used.

Center distance

in
Exact distance with 106 links
20.079
Adjustment vs. your input
+0.079
In pitches
40.2

Allow at least 1 to 2 pitches of take-up (0.500 – 1.000) for chain elongation.

Design check

  • 17-tooth small sprocket: smooth running.
  • Center distance of 40 pitches: within the ideal range (30 to 50 recommended, up to 80).

Length = 2C/p + (N1+N2)/2 + p·((N2−N1)/2π)²/C. Common chain-drive design guidelines; for heavy loads check the power rating in the chain manufacturer's catalog.

Frequently asked questions

How do you calculate roller chain length?

In pitches (links): L = 2C/p + (N1+N2)/2 + p·((N2−N1)/2π)²/C, where C is the center distance, p the pitch and N1, N2 the tooth counts. Round up to an even number, then recalculate the exact center distance for that number of links.

Why use an even number of links?

A roller chain alternates roller links and pin links. With an even number you close it with a standard connecting link; an odd number needs an offset (half) link, which is the weakest point of the chain.

What is the ideal center distance?

30 to 50 times the pitch. Shorter, and the chain wears faster; longer than about 80 pitches, add a guide or idler. Always leave 1 to 2 pitches of adjustment for chain elongation.

How many teeth should the small sprocket have?

17 or more for smooth running. Below 17 teeth chordal action makes the chain pulse and vibrate, and below 9 wear is very fast. Keep the ratio of a single stage at or below 7:1.