How to Compare Dog Years to Human Years

A common old wives' tale said that one dog year was the equivalent to seven human years; however, because a dog is developmentally mature by his first year and a human is not by his seventh, this is untrue.

  1. Considerations

    • A dog's breed, sex, weight and living conditions can all play a large role in determining its life span. Likewise, sex, weight and health also are factors in human life spans. Both female dogs and humans tend to live longer.

    Time Frame

    • Because humans live up to five times longer, on average, than dogs, humans mature at a much slower rate. A 15-year-old human is still very young and developing, while a 15-year-old dog could be considered elderly.

    Theories/Speculation

    • Because it is hard to account for all of the various breeds, health conditions and sex of every dog, it is difficult to come up with an exact figure to compare dog years to human years. However, it is generally acceptable to equate the first year of a dog's life to 15 human years, and then add four, five or seven human years for every calendar year your dog ages, depending on size and breed.