How to compare canine and human years

años caninos

The comparison between the age of dogs and humans has long been the subject of debate and speculation. The popular belief that one canine year is equivalent to seven human years has been widely accepted, but is this equivalence really accurate? In this article, we will explore how to compare canine years to human years in a more accurate and scientifically substantiated manner.

Canine years and human years

The seven-years-for-one theory originated a long time ago and is based on a simple premise: the average life expectancy of a human is approximately seven times that of a dog. However, this formula does not take into account the significant differences in the aging rate between the two species.

Dogs, like humans, experience rapid growth and development during their first years of life. During their first year, dogs reach sexual and physical maturity, which is a critical period in their lives. This initial stage of rapid growth slows down over time, which means that one canine year does not directly translate into seven human years.

In addition, the rate at which dogs age varies by breed and size. Larger breeds tend to age faster than smaller breeds. For example, a large breed dog may be considered old at seven or eight years of age, while a small breed dog may be considered old at ten or even older.


To obtain a more accurate comparison between the age of dogs and humans, scientists have developed different models based on the aging rate of dogs compared to humans. One such model, developed by researchers at the University of California, San Diego, suggests a more accurate formula that takes this variability into account.

According to this model, the first year of a dog’s life is approximately equivalent to 15 human years. The following years add up differently depending on the size of the dog. For example, years two to five for a small dog add up to about four human years each, while for a large dog they add up to about six human years. After six years of age, the formula remains more constant, adding about five human years per year for all breeds and sizes.

This formula provides a more accurate comparison between the age of dogs and humans, taking into account the variability in the rate of aging between different breeds and sizes of dogs. However, it is important to remember that a dog’s age is not only measured in years, but also in terms of health and quality of life.

Factors such as genetics, care, diet and lifestyle play a crucial role in a dog’s longevity and health. A well-cared for and healthy dog can easily exceed the average life expectancy of its breed, while a dog that does not receive proper care can age prematurely and experience health problems.

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