Dog Years Calculator

Why ×7 was always wrong

The multiply-by-7 rule was never based on real biology — it's an old rule of thumb from comparing average human and dog lifespans, and it badly misrepresents how aging actually works. Dogs mature much faster early in life (a 1-year-old dog is already roughly as biologically mature as a 30-year-old human) and then age more slowly per year after that, not at a steady 7-to-1 ratio throughout life.

Where this formula comes from

This calculator uses the logarithmic formula published from a 2019 UC San Diego study that compared DNA methylation patterns (an epigenetic aging marker) between dogs and humans: human age = 16 × ln(dog age) + 31. It's a major improvement over ×7, but it was derived primarily from Labrador Retrievers — small and giant breeds age at meaningfully different rates, so treat the result as a reasonable estimate, not a precise figure for every breed.