DogYearsDog years to human years
Dog years to human years, in one line: forget ×7. Year one counts as 15, year two brings the total to 24, and every year after that adds 4 to 7 depending on your dog's adult size.
Step 1 — first year
A 1-year-old dog ≈ a 15-year-old human, whatever the size. Puppies grow up fast.
Step 2 — second year
By the second birthday the total is about 24 human years — a young adult in both species.
Step 3 — every year after
Add 4 (small), 5 (medium), 6 (large) or 7 (giant) human years per dog year.
A worked example. A 5-year-old medium dog: 24 for the first two years, plus 3 × 5 for years three to five, equals 39 human years. The old rule would say 35 — close here by luck, wildly wrong for a puppy (7 instead of 15) and for an old giant dog (105 instead of the chart's 116 at age 15, or 72 instead of 85 for a 10-year-old giant by some readings). The curve is the point.
For the full 1–20 table, see the dog years chart; to convert a specific dog instantly, use the calculator; for the DNA-based alternative, read about the epigenetic formula.