How can a person tell a cats age when its a stray?

Answer 1

You can make a rough guess based on bone size and the amount of gray/white hair in the muzzle. However, for a more accurate guess, you should let a vet take a look at the cat.

Please do not try to handle a stray cat as if it were a house cat - while some strays are very nice and like people, most have learned (painfully) that humans are dangerous to them and will scratch and bite you to get away. This puts you at risk for diseases like rabies and cat scratch fever.