Roller Chain Length & Center Distance CalculatorROLLER CHAIN CENTER DISTANCE

1. 1Pick the chain number (e.g. No.40, 12.7 mm pitch).
2. 2Enter the tooth counts of the small (z1) and large (z2) sprocket.
3. 3Enter the center distance your design would like.
4. 4Read the link count rounded to an even number, the resulting actual center distance and the error ΔC.
5. 5Set your motor mount or tensioner to the actual center distance, and open both sprockets in the 3D generator.

Chain length is expressed as a number of links Lp. With pitch p, tooth counts z1, z2 and a desired center distance C, the JIS B 1801 approximation gives a theoretical link count, which is then rounded to the nearest even number. The inverse formula turns that whole number of links back into the actual center distance; the difference ΔC is the adjustment your design must allow. Pitch diameters d = p / sin(180°/z) and outside diameters of both sprockets are listed for drawing or for generating sprocket models.

Use at least 17 teeth on the small sprocket, keep its wrap angle above 120° and a single-stage ratio within 7:1. A center distance of 30–50 pitches works best. Leave some slack: for horizontal drives the sag should be about 2% of the center distance. 3D-printed sprockets suit slow, light-duty drives and prototypes; for production or heavy loads use steel sprockets — send the model to Orinovate for a CNC or metal-printing quote.

Lp = 2C/p + (z1 + z2)/2 + ((z2 − z1)/2π)² · p/C
Lp → nearest even number
C = p/4 · [ (Lp − (z1+z2)/2) + √( (Lp − (z1+z2)/2)² − 8((z2 − z1)/2π)² ) ]
d = p / sin(180°/z)
Do ≈ p · (0.6 + cot(180°/z))
i = z2 / z1, L = Lp · p

Results are for design reference only; confirm against supplier catalogues and the applicable standards before manufacturing.