Originally Posted by San Rensho
...12 inches is hard to measure with calipers.
Thanks.
You can read 1/16" with a steel rule or even tape measure. It may be preferable to measure 12 links instead of one. Measuring 12 is like using statisical average for 12 links. Measuring one just gives the length of one link and assumes all links wear the same.
FWIW, Park tool sells a go / no go chain gauge. If the tool can fit into the chain, then it's time to change.