Pet age to human years calculator

The old "multiply by seven" rule is a myth. Pets age fastest in their first couple of years and then slow down, so Whiskerclock uses a curve instead of a flat multiplier.

Dogs

A dog's first year covers roughly 15 human years of development. After that, ageing tapers off — we use a logarithmic curve based on the epigenetic-clock research from UC San Diego, which compares DNA methylation in dogs and humans.

• age ≤ 1 → age × 15
• 1 < age < 2 → smooth blend between the two
• age ≥ 2 → 16 × ln(age) + 31

Those two curves don't quite meet at the one-year mark, so we ease from one into the other across the second year rather than letting the number leap. It's the same reason a puppy doesn't turn into an adult dog overnight.

Cats

Cats front-load their ageing too: the first year is about 15 human years, the second adds roughly 9 more, and every year after that adds about 4.

• age ≤ 1 → age × 15
• 1 < age ≤ 2 → 15 + (age − 1) × 9
• age > 2 → 24 + (age − 2) × 4

These are population averages. Breed, size, and health all shift the real number — large dogs age faster than small ones, for instance. Treat the result as a fun estimate, not a vet's assessment.