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Calculating Dog Age in Human Years

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A small mixed-breed dog wearing a pink party hat.

You may have heard of the traditional idea that to calculate a dog’s age in human years, you multiply their age by seven. You might be surprised to find out that this rule is a myth. 

As the American Veterinary Medical Association says, “Contrary to popular belief, dogs do not age at a rate of seven human years per dog year.”

While there is no exact formula for calculating a dog’s age in human years, there are a few factors that affect aging in dogs. The latest scientific research using DNA methylation has also introduced new methods for understanding dog age.

Here, we’ll explain how to use these factors—as well as DNA methylation—to better estimate a dog’s age in human years.

Factors affecting dog age in human years

As mentioned above, the “multiply by seven” rule is not an accurate way to calculate a dog’s age in human years. Different dogs age at different rates, so there is no single rule that applies to every dog equally. 

There are several factors affecting how old a dog is in human years, including:

  • Size
  • Breed
  • Genetics
  • Lifestyle

Keep in mind that these aren’t the only factors affecting how old or young a dog acts and feels.  As you probably already know, some dogs that are senior in dog years can still act like puppies at heart. The old adage that “age is just a number” is true for us and our dogs.

How to calculate dog age in human years

Dogs generally go through five major life stages: puppy, young adult, mature adult, senior, and geriatric. These life stages can be roughly translated into the equivalent human life stages. 

The specific dog age for each life stage varies for small, medium, large, and giant dogs.

Dog life stages

Puppy Young Adult Mature Adult Senior Geriatric
Small (up to 20 lbs) < 6 months 6 months to 5 years 5–11 years 11–14 years 14+ years
Medium (21-50 lbs) < 9 months 9 months to 4 years 4–9 years 9–12 years 12+ years
Large (51-100 lbs) < 15 months 15 months to 3 years 3–8 years 8–11 years 11+ years
Giant (over 100 lbs) < 24 months 24 months to 3 years 3–6 years 6–8 years 8+ years

Although this chart gives a general idea of when a dog may enter a new life stage, it’s important to remember there is a large amount of individual variation. Just as in people, a dog’s genetics, nutrition, and environment (among other things) can play a role in how quickly they age. 

Using DNA to calculate dog age in human years

In addition to these life stages, recent advances in DNA research are giving scientists new ways to think about dog age. 

Researchers at the University of California San Diego (UCSD) developed a method that uses DNA methylation to compare human age and dog age. When they matched dog age to human age, they also found that the comparison is not a 1:7 ratio over time, further showing that the “multiply by seven” rule isn’t accurate.

One limitation of this method from UCSD is that it was only developed for one dog breed, so it doesn’t apply to all breeds equally. Some breeds are known to have longer lifespans or mature at different rates than others.

Still, studying the relationship between DNA methylation and age has become an exciting area of science. Thanks to advances in methylation research over the past 10 years, there are published papers showing how methylation technology works for dogs, humans, and many other mammals. 

How to estimate dog age

Now there’s a new way to use DNA methylation to estimate your dog’s age. 

At Embark, we’ve developed a Dog Age Test that estimates your dog’s age and birthday based on their methylation profile. The Embark Age Test uses the amount and position of DNA methylation as a type of “clock” to estimate how old your dog is (Horvath et al. 2022). Our Age Test model relies on methylation data from 2,000+ dogs of varying breeds, sizes, and ages. 

Dog Age Test
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Whether you measure their age in human years or dog years, celebrate your dog’s birthday with the Age Test today!

Caring for your dog at every age

Learn more about the different dog life stages and health considerations to keep in mind as your dog celebrates more birthdays.

Mimi Padmabandu Contributor

Mimi Padmabandu is a scientific writer and Content Strategy Lead at Embark Veterinary. She has over a decade of experience writing about science and genomics for leading biotechnology companies. She holds a bachelor's degree in Molecular, Cell, and Developmental Biology from UCLA and a master’s degree in Early Modern English Literature from King’s College London.

Read more about Mimi Padmabandu

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