Dog Age Calculator - Convert Dog Years to Human Years (Size-Adjusted)

Why the 7-year rule is wrong

Dogs mature rapidly. By the end of year one a dog is roughly the equivalent of a fifteen-year-old human. Year two adds about another nine human years, taking a two-year-old dog to around twenty-four. After that, the pace slows but it depends heavily on breed size.

Small breeds age more slowly per year, often living fourteen to sixteen years. Giant breeds age much faster - a six-year-old Great Dane is already a senior, while a six-year-old Chihuahua is still a young adult.

Size-based aging rates after age two

After the rapid first two years, our calculator uses size-adjusted multipliers: roughly four human years per dog year for small breeds, five for medium, six for large and eight for giant breeds. This matches the median life-expectancy data published by large veterinary studies.

When does my dog become a senior?

Small breeds (under 20 lb) typically reach senior status around age ten. Medium breeds around age eight to nine. Large breeds around seven. Giant breeds as early as six. Senior status is a cue to start twice-yearly vet visits, adjust calories down by about twenty percent and consider joint support supplements.

How to keep your dog younger for longer

Three habits consistently extend healthy lifespan: keeping a dog lean (overweight dogs live up to two years less), daily exercise appropriate to age, and consistent dental care. Brush teeth several times a week and schedule professional cleanings as your vet recommends.

• Maintain a body condition score of 4-5 out of 9.
• Walk at least 30 minutes a day for most adult dogs.
• Brush teeth three or more times per week.
• Vet checkups twice a year after age seven.