About the Dog Age Calculator

Dog aging is fastest early in life: the first year equals about 15 human years (puppies reach sexual maturity quickly), the second adds roughly 9 (reaching 24), and after that large breeds age ~6 human years per dog year, medium ~5, small ~4.

Why the Old Rule Fails

The '1 dog year = 7 human years' rule assumed dogs live ~10 years and humans ~70, but it flattens the real curve: it makes a 1-year-old dog 7 (too young) and a 10-year-old dog 70 (about right for a small dog, old for a large one). Stage-based care — puppy, adult, senior — is what actually matters for health decisions.