Dog Years to Human Years: Chart by Size

A 7-year-old dog is about 44 in human years if it is small, 49 if it is medium-sized, 52 if it is large and 55 if it is a giant breed. The old rule of multiplying by seven gets most of these wrong, because dogs age very quickly at first and big dogs age faster later on.

Dog years to human years chart

Find your dog's age on the left and its size along the top. Sizes are by adult weight: small is under 20 lb, medium 20–50 lb, large 50–90 lb and giant over 90 lb.

The chart uses the same size-based aging curves as our calculator: 12–15 human years for the first year and 20–24 by the second birthday (bigger dogs at the lower end), then a set number of years for each dog year that depends on size.

Why the 7-year rule is wrong

Multiplying by seven assumes a dog ages at the same steady pace all its life. It doesn't. A one-year-old dog is already sexually mature and close to its adult size, much more like a teenager than a seven-year-old child. By two, most dogs are the equivalent of a person in their early twenties.

After that, aging slows down, but not evenly. Small dogs add about 4 human years for each extra year, medium dogs about 5, large dogs about 6 and giant breeds about 7. That is why a 10-year-old Chihuahua is middle-aged while a 10-year-old Great Dane is elderly.

Why big dogs age faster

It seems backwards, since large animals usually live longer than small ones. Within dogs, though, the opposite holds: giant breeds often live 8–10 years while many small breeds reach 14–16. Big dogs grow extremely fast as puppies and appear to age faster once they are adults, so problems like arthritis, heart disease and some cancers show up earlier.

When is a dog a senior?

• Small and medium dogs: from about 8–10 years.
• Large dogs: from about 7–8 years.
• Giant breeds: from as early as 5–6 years.

Senior dogs do best with check-ups every six months rather than once a year. Many age-related problems, including kidney disease, dental disease and arthritis, develop slowly, and a vet can often pick them up before you notice anything at home.

Signs your dog is getting older

• Graying around the muzzle and eyes
• Sleeping more and slowing down on walks
• Stiffness when getting up, or reluctance to jump or use stairs
• Cloudy eyes or reduced hearing
• Weight gain from lower activity, or weight loss from illness

Making the most of your dog's later years

Keeping a dog lean is one of the most effective things you can do for a long life. Lean dogs consistently live longer and develop arthritis later than overweight dogs. Our dog food calculator gives a daily starting amount, and the dog weight tools help you keep track.

Regular gentle exercise, dental care and a soft, easy-to-reach bed all help an older dog stay comfortable. Any sudden change, such as drinking much more water, losing weight or a new lump, is worth a vet visit rather than waiting for the next check-up.