How old is your dog
in dog years?

Unlike cats, dogs don't age on a single, universal curve — size plays a huge role. In the first two years, all dogs age at roughly the same fast pace: a one-year-old dog is already about as physically mature as a 15-year-old human, and by age two that reaches roughly 24 human-equivalent years, regardless of size.

After that, the curves split apart. Small breeds like Chihuahuas and Yorkshire Terriers age more slowly from here on, often living well into their teens. Giant breeds like Great Danes and Saint Bernards age considerably faster after that early growth spurt, typically reaching their senior years by age 6-8 and living, on average, several years less than a small dog.

That's the core reason a single "multiply by seven" rule of thumb doesn't work for dogs the way it's sometimes (inaccurately) applied to pets in general — the right multiplier depends heavily on how big your dog is.

Vets typically group dogs into six broad life stages — puppy, junior, adult, mature, senior, and geriatric — because care needs (diet, activity, and what to watch for health-wise) shift meaningfully from one stage to the next, and those stages arrive earlier for bigger dogs. Breed matters too: some breeds are prone to specific health conditions that become more relevant at certain ages. Browse breed-specific care guides →