Last verified: August 2026 · Methodology
Dog age calculator
Convert your dog’s age into an approximate human-year equivalent using size-based rates — not the outdated ×7 rule. First year ≈ 15 human years, second ≈ +9, then +4 to +7 per year by adult size.
Approximate human-year age
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Educational estimate only. Not a substitute for veterinary advice. Method inspired by common AVMA-discussed aging patterns; breed longevity varies.
Why size matters
Larger dogs often age faster after adulthood than smaller dogs. ChronoCalc’s bands follow that pattern: after the shared 15 + 9 early years, each additional dog year maps to roughly 4 (small), 5 (medium), 6 (large), or 7 (giant) human years.
Prefer calendar age for humans? Use How old am I.
Dog age FAQ
Is “one dog year = seven human years” accurate?
No. That myth oversimplifies aging. Dogs mature quickly in the first two years, then age at rates that depend heavily on adult size. ChronoCalc uses a size-banded estimate commonly described in veterinary education materials.
What size band should I pick?
Use expected adult weight: small under ~20 lb, medium 20–50 lb, large 50–90 lb, giant over ~90 lb. When unsure, medium is a reasonable default.
Is this a medical diagnosis?
No. It is an educational estimate. Ask your veterinarian about breed-specific longevity and senior-care timing.