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Engineering Kit

Chain sprocket calculator

A free online chain sprocket calculator for roller chain drives. Set the chain pitch, the driver and driven tooth counts and the centre distance, and the drive redraws as you move each slider, so an impossible layout shows up before you order the parts.

Try the live demo
Chain drive schematic with a 20 tooth driver sprocket, a smaller driven sprocket, the roller chain wrap and the centre distance dimension.

Try it in your browser

Drive the inputs and watch the geometry redraw in real time. The preview deliberately stops short of the numbers: chain length in whole pitches, centre distance, sprocket pitch diameter and speed ratio all stay in the Android app.

Chain drive demo

Adjust pitch, tooth counts and centre distance to reshape the chain wrap.

12.7 mm
21 T
13 T
420 mm

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What the chain sprocket calculator works out

Chain Sprocket Calculator is deliberately narrow: it solves one sizing problem completely, with the assumptions written down next to the result.

Chain length
in whole pitches and in millimetres or inches, rounded to an even link count.
Centre distance
corrected back from the rounded chain length, so the take-up travel is real.
Speed ratio
driver to driven, with the output speed for a given input RPM.
Pitch diameter
for each sprocket, plus the outside and bore clearances you need for a guard.
Wrap angle
on the small sprocket, which drives the number of teeth actually carrying load.

Typical jobs

100% offline

Chain Sprocket Calculator for Android

The Android app returns the numerical chain length, the corrected centre distance, every pitch diameter and the full ratio table, in metric or imperial units, entirely offline. No account, no sign-in, no data connection.

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