Every year of a dog's life equals seven human years, so your six-year-old labrador is really 42. It is the rule everyone reaches for at the vet, simple multiplication that turns your pet's age into a human number.
Dogs do not age on a flat times-seven schedule. They mature extremely fast in the first couple of years, then the rate slows right down. A one-year-old dog is roughly equivalent to a human teenager, already near adult size and sexually mature, which is nowhere near seven human years, and the gap keeps shifting after that. Size and breed matter a lot too: small dogs tend to live longer and age more gently than giant breeds, so a Great Dane and a chihuahua of the same age are not at the same life stage. A 2020 study even proposed a formula based on changes to DNA over time, which produced a curve, not a straight line. The seven-times rule seems to be an old marketing-era simplification. It is a rough, wrong shortcut. Your dog is ageing on its own curve, fast at first, then easing off.