How To Calculate 'Dog Years' Correctly

If you’ve ever multiplied your pup’s age by 7 to get some perspective on how old or young they really are, you’ve probably noticed the formula has its flaws. A new calculation is a bit harder to remember, but gives an answer that may be more accurate.

A Dog Year Is NOT Equivalent To 7 Human Years

Do you know your dog's age in 'dog years'? You know: supposedly a dog is seven dog years old on its first birthday and all that? Well, as it turns out, that figure isn't really accurate at all, and it's thrown even further out of whack when you realise that all dog breeds age at different rates. So if you want to figure out your pooch's actual age in dog years, here's how to do it.

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To come up with the new formula, researchers compared the methylation of Labradors’ DNA with that of humans at different ages. Methylation is a biochemical process that happens to DNA as we age; the older we get, the more methyl groups on our DNA.

The new way to calculate dog years:

According to the study, which has not been peer reviewed, you can plug your dog’s age into this formula to get a roughly equivalent human age:

31 + (16 * ln(AGE))

Copy and paste that formula into your Google search bar, replace “AGE” with your dog’s age, and you’ll get the answer. The “ln” in the formula refers to the natural log function, which Google and most medium-fancy calculators know. (It’s one of those extra buttons you’ll see on the iOS calculator if you turn your phone sideways.)

Here’s how it shakes out for Labradors of various ages:

  • 1 actual year: 31

  • 2 actual years: 42

  • 3 actual years: 49

  • 4 actual years: 53

  • 5 actual years: 57

  • 6 actual years: 60

  • 7 actual years: 62

  • 8 actual years: 64

  • 9 actual years: 66

  • 10 actual years: 68

  • 11 actual years: 69

  • 12 actual years: 71

  • 13 actual years: 72

  • 14 actual years: 73

  • 15 actual years: 74

This makes a little more sense than the seven years rule: your pup is like a human adult by the time she reaches her first birthday, becomes middle-aged over the next few years, and enters senior citizen territory around 9 years old.

Even if this formula ends up getting other scientists’ OK, it has its limitations. Different dogs age at different rates, and this was calibrated for just one breed.

Some terriers will live to be 15 to 20 years old, for example, while giant breeds like Great Danes may only live to about 8. There are also different ways to think of ageing besides DNA methylation. For example, how physically and mentally mature is your growing puppy? That’s a trickier question.


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