Dog Age Calculator

The idea that you multiply a dog’s age by seven is one of the stickiest myths in pet lore — and it is wrong. Dogs do not age at a steady rate, and they do not all age at the same rate. A more honest answer front-loads the early years and then lets breed size set the pace.

Three rules turn a dog’s age and size into a human-equivalent age. It is the widely-cited AVMA-style mapping — an approximation, but a far better one than ×7.

1. 1

   Count the first year as ~15

   A dog’s first year is worth about 15 human years. For a puppy under one, scale within that first 15 — six months is roughly 7.5.

   0.5 yr × 15 = 7.5 human years
2. 2

   Add ~9 for the second year

   The second year adds about 9 more, so a two-year-old dog of any size lands at roughly 24 human years. Size has barely diverged yet.

   15 + 9 = 24 at age 2
3. 3

   Add a per-size amount each year after 2

   From the third year on, add a fixed amount per year that depends on breed size: +4 small, +5 medium, +6 large, +7 giant.

   medium, age 5 → 24 + 3×5 = 39

Watch a 10-year-old dog’s human age shift as the breed size changes — the clearest demonstration of why a single multiplier cannot be right.

Every dog age from 1 to 16, converted to human years for all four breed sizes. Tap a size to highlight its column — the shareable lookup for “how old is my dog in human years?”

How this calculator groups dogs by adult weight, and the per-year increment each group adds after age two.

A dog’s number is only half the story — the life stage tells you what to expect. Big breeds reach each stage sooner than small ones.

The errors that make dog-age math wrong — and the facts that keep it honest.

One quick conversion that shapes how we care for our dogs.

Common questions