1/16" elongation over 12" amounts to about 0.5%, and 1/32" would of course be half that. The type of chain checker I use has feelers for 1.0% and 0.75% . So your standard is quit high by comparison. Then another issue is how much elongation is the trigger to change the chain, which amounts to cost of replacing chains to replacing the chainrings and cassettes. I will definitely use both my gauge and a ruler, if for no other reason to check calibration on the checker.

http://www.google.com/imgres?q=chain...9,r:5,s:0,i:94

Just ain't no simple answer.