How to Calculate Dog Years?

Are you wondering how to calculate dog years in order to figure out your dogs age in comparison to a humans? Dogs age differently than we do. They mature quickly and live much shorter lives. You may have heard it said that one dog year is equivalent to seven human years, but this is not an accurate statement. All dogs are not the same, but a breed will reveal similarities.

Happy face at dog friendly McAllister Park in San Antonio.  Dogs know how to have fun at the dog park.

Dogs mature much faster than we do, especially smaller breeds which tend to reach maturity before larger breeds. Even among their own kind there is a wide age gap. Figuring out how to calculate dog years will depend on breed and size. Use the table below to determine how old your dog is as it relates to human years.

Dog Years to Human Years

The following calculations table shows the dog age (in years) in the far left column. Each column thereafter reveals the size of the dog, and the age the dog would be in human years.

Age Small breedsMedium breedsLarge breeds

I used the Pedigree dog calculator to figure out each age in relation to its size. A dog who is 35 pounds and under may fall into the small breed category. Dogs weighing 35 – 65 pounds are considered to be a medium breed. Dogs ranging anywhere from 55 – 85 pounds are placed among the large breed category. The column for giant breed dogs has been omitted because its results would nearly be identical to that of the large breed.

Discussing the Calculations

While figuring out how to calculate dog years, you will notice that every breed matures quickly the first year. Medium breeds seem to mature the quickest until around age five, at this point larger breeds jump out in front. The ages of all breeds are closer together in years one and four, although the small and large breeds flip positions.

After the second year, smaller breeds seem to gain four human years each year while medium breeds gain five. However, larger breeds gain seven human years each year after the first. This is probably why it is said that one dog year is equal to seven human years. Seven years would seem to make sense for most of the life of a larger dog. All dogs reach adulthood very quickly compared to us, but the smaller breeds age less quickly around year three.

In order to calculate dog years I must know her current size and age.

The chart shows that the aging of dogs is complex compared to humans. Fortunately it also shows you how to calculate dog years. The size of a dog is a good indicator of how she will age. My Rhodesian Ridgeback is just over two years old, and 65 pounds. Her age is equivalent to that of a 19-20 year old female. If she were able to live 13 more years she would be like a 110 year old woman! However, if she were a small 15 year old dog, she would only be like a 76 year old woman. Dog facts are pretty wild, huh?


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