How to tell a dog's age

tailculator 4 MIN READ UPDATED May 2026

If you adopted a dog with no paperwork, you may not know its age. You can still make a good estimate. Vets do it every day, mostly by looking at a few things.

Teeth tell the most

Teeth are the single best clue in a younger dog.

Teeth are less reliable in older dogs, because dental care and chewing habits vary so much.

Other clues

None of these is exact. A vet weighing all of them together can usually estimate within a year or two.

Once you have an estimate

A vet’s estimate gives you a number in dog years. To understand what that means for your dog’s life stage, put it into the dog age calculator with your dog’s breed or size. A “5-year-old” rescue is a young adult if it is small, and approaching senior if it is a giant breed.

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