How Old Is My Dog in Human Years?
The "multiply by 7" rule is a myth — real dog aging depends heavily on size, and it's front-loaded in the first two years.
Why "1 dog year = 7 human years" is wrong
The x7 rule assumes dogs age at a constant rate their whole life and that all breeds age the same way. Neither is true. A one-year-old dog isn't 7 in human terms — it's closer to 15, since dogs reach physical and sexual maturity far faster than humans do in year one. After that early sprint, aging slows down, and how much it slows depends heavily on your dog's adult size.
The first two years are the big jump
Most of a dog's "fast" aging happens before their second birthday. By age one, a dog is roughly equivalent to a 15-year-old human — already through infancy, childhood, and into adolescence. By age two, most dogs are around 24 in human years, comparable to a young adult. This is true across nearly all sizes; it's after year two that small and large breeds start to diverge.
After year two, size matters
Once a dog is past the rapid early-growth phase, aging becomes more gradual — but larger breeds age faster in their adult and senior years than small breeds do. A small dog might add roughly 4 human years for every dog year after age two, while a giant breed can add 6 or more. That's why a 10-year-old Great Dane is genuinely much older, biologically, than a 10-year-old Chihuahua, even though they're the same number of years old on the calendar.
Get your dog's exact age
For an exact number based on your dog's actual size, use our Dog Age Calculator — it applies this size-adjusted curve instead of the flat x7 rule. If you'd rather see the numbers laid out by size at a glance, check our Dog Age Chart. And if your dog is still under two, the aging math works a little differently — see Puppy Age in Human Years for that first stretch specifically.