measuring is easier for me :D,
btw chain failure at 100,000 kms means that either the design is really poor or some sort of lube failure is going on. Such as seen on the old mazda 808, 323 etc engines, it actually had a pair of hook shaped oilers for the chain which would get smashed up if the tensioner failed. Mechanics almost never replaced that part,
I expect a timing chain to last at least 200,000 kms unless the chain is an extemely sloppy product made by chinese slaves.