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Dog Years: How Old Is My Dog In Human Years?

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We’ve all done it, haven’t we? There’s something irresistible about the idea of guessing our pet’s age in human years. But how do you make an accurate assessment of your dog’s age?

The Old Myth

You might have heard it said that one dog year equals 8 human years. But this method of estimating your dog’s age is far from accurate because dogs mature at a different rate to humans. For instance, a one-year-old dog is almost an adult whereas an eight-year-old human is still very much a child. You must also remember that dogs of certain breeds will often live to 15 years of age whereas humans rarely make it to 120. The oldest dog for which there are reliable records lived to be 29. No human has ever lived to be 232!

The Calculation

Dogs progress to adulthood far quicker than humans. Roughly speaking, you can consider the first year of your dog’s life to be equivalent to 15 human years. Your pooch’s second year of life is equivalent to 9 human years. After that dogs age at the rate of 3 to 5 human years every year depending on a variety of factors.

Size Matters

It is important to consider the breed of your dog when estimating its human age. Lifespan is closely related to size in dogs with larger breeds often living only 7 or 8 years whereas a miniature poodle could be expected to live for 15 years and may survive into its 20s. Pedigree dogs tend to live shorter lives than cross-breeds but there are exceptions to this rule.

The Statistics

The Kennel Club conducts surveys regularly to assess the impact of breed on lifespan. In addition, a recent survey looked at the records of over 100,000 dogs in England and found that the average lifespan of a pooch was 12 years. The longest living breeds were the Miniature Poodle, Bearded Collie, Border Collie and Miniature Dachshund. The shortest living breeds were the Dogue de Bordeaux and the Great Dane. A further survey revealed that cross-bred dogs lived an average of 1.2 years longer than purebred animals.


If you own a cross-breed and are unsure as to its background or parentage you can send off a swab for genetic analysis. The test will reveal your pet’s breed mix with reasonable accuracy. This will help you to asses how old it is in human years and how long it might live.

Online Calculators

There are online tools available which will give you an approximation of your dog’s age in human years. These take into account breed and size. The calculators are entertaining but you must remember that age calculation is an inexact science. Your dog may be uncharacteristically youthful or old before its time. It may live longer than anticipated or die surprisingly young. Lifestyle factors will impact your dog’s longevity just as they do with humans. Obese dogs will not live as long as fit dogs of the correct weight.


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