Here’s how to figure a dog’s age in dog years

Everybody wonders sometimes – how do you figure a dog’s age in dog years, anyway?

It’s  common question that comes with having pets we love in our daily lives, but one that can be tricky to calculate. (Math is hard.) But how do you figure a dog’s age in dog years?

Turns out, probably not like what you think.

Traditionally, one human year is reckoned as seven dog years, which works out to roughly one dog year equaling seven human weeks. For each human year, you multiply by seven, and then count the weeks to get a rough estimate as to how old your doggo is.

So, for example, Trusty, a six-year-old dog born in early March, would be about 45 in human years by late August. (Human years x dog years + whatever’s left over, 6 x 7 = 42 + 21 weeks = 45).

This is the way most of us learned how to calculate canine lifespans.

There’s just a few problems with this method: First, most people don’t know exactly when their dog was born, so they may use their adoption date as a rough estimate. That throws off the calculations right from the start. Second, it’s surprisingly difficult to count weeks by sevens. Third, it’s not accurate.

According to an article on the American Kennel Club (AKC) website, the American Veterinary Medicine Association (AMVA) says it’s probably more accurate that the first human year of a dog’s life is roughly 15 in dog years, the second human year is roughly nine dog years, and then every human year after that is about five dog years.

By this calculation, Trusty the six-year-old dog used in the example above would be about 44 in dog years. Still about the same, but fast-forward another three years, and by the old reckoning Trusty would be around 66, while by the AVMA’s formula, he would be only 59. That’s considerably younger than 66, if you think about how the aging process works.

William Fortney of Kansas State University told the Wall Street Journal that he thought the seven-year rule was developed as a marketing tool to make sure owners brought their pets in for a checkup at least once a year. (After all, vet school is incredibly expensive.)

And making things even more complicated, some breeds live longer – a smaller dog like a Beagle will be much more likely to live longer than a larger breed like a Great Dane, for example.

Perhaps accounting for some of the reason smaller breeds live longer, the AKC article reports that according to research done by German evolutionary biologist Cornelia Kraus, for every 4.4 pounds added to a dog’s weight, their life expectancy drops by about a month. It is unknown why this could be.

Basically, here’s what it boils down to: Dog science is complicated. The seven-year rule isn’t all that accurate, but it’s easy to remember.