Over the summer, my family adopted a puppy Maltipoo (Maltese + Poodle). He was almost 8 weeks old when we brought him home, but I wanted to know exactly how old my cutie-pawtooty was. This got me thinking about how dog years are calculated.

The “one year for a human is the same as seven years for a dog” is based on the proportion for the average lifespan of a particular breed of dog and the average lifespan of a human. Larger dogs, like labradors and German shepherds, follow the seven years ratio that we assume to be the same for every breed. Smaller dogs, like poodles and terriers, typically live longer, so the seven years ratio doesn’t accurately calculate their equivalent human age.

To find your dog’s accurate human equivalent age (HEA), you need to know two things: how old your dog is (the more accurate, the better) and the average lifespan of your dog. A quick Google search can tell you how long your breed of dog typically lives. (Note: if Google gives you an answer that is something like “10-14 years” you need to average that too.)

We also need to know what the average lifespan for a human is. This answer varies by source. For my calculations, I usually use 80 as the average human lifespan.

Now that we have all of our numbers, let’s look at the proportion:

What a “dog year” really is = human average life span/dog breed average lifespan

This formula will give you the “dog year” ratio. You can round this number to the nearest year for simple calculations or to the nearest hundredth for more accuracy. To find your dog’s HEA, simply multiply the dog year ratio that you just calculated, and how old your dog is. Now you can accurately celebrate your dog’s birthday!

Note: This can also work with other animals too (like cats, for you cat people).