This article was updated on February 19th, 2026

Wondering ‘Exactly how old is my dog?’ in human years? As this site is all about caring for older dogs, we thought it would be a good idea to add a page that helps us figure out  how ‘old’ our dogs really are. If you already know your dog’s age but are wondering how old your dog is in human years equivalent, use our calculator below.

The two easiest methods:

1. Based on your dog’s breed: use our “dog years to human years” Calculator

When estimating how old your dog is in human years, the primary factor to consider is your dog’s breed. Indeed, the longest-lived breeds live as much as 75% longer than the shorter-lived breeds. Research also shows that neutering status, and, to a lesser extent, sex are important factors to take into account. Use the calculator below to estimate your dog’s age in human years:

2. Based on your dog’s size: estimate your dog’s age based on their size

All in all trying to figure out how old your dog is in ‘dog years’ v ‘human years’ isn’t an exact science. If your dog is mixed breed or if you don’t know your dog’s breed, the next most important factor to consider is size/weight. To make it a little easier, we have put together this table that translates ‘dog years’ to ‘human years’ for small, medium and large breeds.

At What Age is a Dog Considered to be ‘Old’?

Because dogs age at different rates, there’s no single age at which Fido becomes a ‘senior citizen’.

Rule-of-thumb says that the last quarter of his life is considered ‘old age’. Small breeds routinely live to be 12 or 15 years old, so they’re going to be ‘seniors’ by around 9 or 10. X-large and giant breeds may have an average life expectancy of 8 or 9. That means they’re ‘old’ by the time they’re 6 or 7.

Medium sized dogs fall somewhere in the middle.

We all know the common adage ‘One human year equals seven dog years’… but although that works okay as a ‘rule of thumb’ for an average-sized dog, it’s not accurate at all if you’re talking about small, or large/giant breeds.

That’s because the big ‘uns age much more quickly than their smaller cousins.

Large and giant breeds are very slow to mature, and don’t become adults until they’re two, or sometimes even three, years old (compared to small breeds who can be fully adult at one year).

But big dogs age and decline quickly, giving them fewer ‘in-between’  years. Seniority comes all too quickly to our biggest dogs.

On the other end of the spectrum, small dogs mature quickly, but stay youthful for much longer.

Other things can factor in as well, including diet, overall health, breed-specific traits, general care and more.