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Chain Drive Length Calculator

Work out chain drive length instantly with clear inputs, formula shown and shareable results.

About Chain Drive Length Calculator

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.

Formula

Chain length

L pitches = 2C/p + (N1 + N2)/2 + [(N2 - N1)/(2 pi)]² / (C/p)

Worked example

With the default values below, Chain Drive Length Calculator returns Chain length to order of 112. Change any input above and every figure here is recalculated in your browser.

Inputs used

Small sprocket teethminimum 6
17
Large sprocket teethminimum 6
45
Centre distanceminimum 0.5 in
20 in
Chain pitchminimum 0.1 in
0.5 in

Results

Chain length to order
112 pitches
Calculated length
111.50 pitches
Chain length
56.00 in
Drive ratio
2.647

Step by step

  1. 1Values used
  2. 2Chain length
  3. 3Chain length to order= 112 pitches
  4. 4Calculated length= 111.50 pitches
  5. 5Chain length= 56.00 in
  6. 6Drive ratio= 2.647

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Chain Drive Length figure worked out?

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).

Why avoid an odd number of pitches?

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.

What values do I need to enter?

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.

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