Dogs don't age at a steady seven-years-per-year rate — that old rule of thumb is a myth. Puppies mature fast in their first two years, then the pace slows and depends heavily on breed size: smaller dogs generally live longer and age more slowly than giant breeds.
This calculator uses the widely-accepted veterinary model — roughly 15 human years for the first dog year, about 9 more for the second, then 4–7 human years each year after depending on size — to give a realistic estimate of your dog's age in human years.
Frequently asked questions
Is the 7-year rule accurate?
No. Dogs age much faster in their first two years, then slower — and large breeds age quicker than small ones. A flat ×7 over-estimates young dogs and under-estimates old giant breeds.
How is dog age calculated here?
Year one ≈ 15 human years, year two adds ≈ 9 (24 total), then each additional year adds 4 (small), 5 (medium), 6 (large) or 7 (giant) human years.
Why does breed size matter?
Larger dogs have shorter lifespans and reach old age sooner, so each calendar year counts for more human years than it does for a small dog.