Dog age calculator (in human years)
Convert your dog's age to human years, taking the breed size into account.
Estimate: the 1st year ≈ 15 human years, the 2nd +9, then 4–6 per year by size (large dogs age faster).
How the calculation works
The first year equals about 15 human years; the second adds 9 more (24 total). After that, each year is worth 4 (small) to 6 (large) human years.
Examples
- A 5-year-old medium dog: ~24 + (3 × 5) = ~39 human years.
- A 1-year-old puppy already equals ~15 human years (a teenager).
Frequently asked questions
Why do large dogs age faster?
Large breeds have shorter lifespans, so each year "counts" more in human years.
Is the "×7" rule correct?
Not really. Multiplying by 7 is crude — dogs mature fast in the first 2 years and slower after. This calculator uses that real pace.
What about a cat's age?
Similar, but cats live longer and the math differs a bit. This tool is for dogs.
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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources