How to determine the proper length of a roller chain

Roller chains consist of a certain number of inner and outer links in endless formations.
Generally, even numbers of links (including a chain coupling) are preferred. Every chain to be linked with a chain coupling must start with an inner link (must consist of an odd number of links without the coupling ).

EXAMPLE:
The requirement is for 1 metre of 16 B-1 chain. The exact length of the chain is determined as follows:
1. First, the pitch of the chain in question must be identified (manufacturer's table may be used). In this case, the pitch is 25.4 mm.
2. The ratio 1 metre/pitch is 1000/25.4 = 39.37 –  this value should always be rounded to the nearest odd number (this means an inner link obtained from both sides of the chain) – in this case 39 links are required, i.e. (39*25.4) 990.6 mm of the chain.
3. When the chain is linked with an appropriate coupling, the result is a chain drive with 40 links (incl. the coupling) 1,016 mm long.

If, due to the length requirement, a chain with an odd number of links with a coupling must be applied, a so-called reduction - halflink - is used (Attention: an ordinary reduction will transfer up to 65 % of the permitted chain load).
Generally, it is recommended to avoid the use of chain reductions.