Is it true that 1 dog year = 7 human years?

No. That myth oversimplifies. Dogs age rapidly in their first two years, then more slowly. Size also matters — small breeds live longer than giant breeds. This tool uses modern size-adjusted formulas.

What formula is used for dogs?

For the first 2 years: 15 (year 1) and +9 (year 2) = 24 human years at age 2. After that, we add 4–7 human years per dog year depending on size (small: +4, medium: +5, large: +6, giant: +7).

What formula is used for cats?

Year 1 = 15 human years, year 2 = +9 (24 human years). Each subsequent cat year = +4 human years — a commonly cited veterinary benchmark.

Breed affects lifespan, but size is the most established factor. Giant breeds (Great Danes, Mastiffs) age fastest; toy breeds (Chihuahuas, Pomeranians) age slowest.

Pet Age Calculator (Dog & Cat Years)

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Free pet age calculator. Convert your dog or cat's age to human-equivalent years using up-to-date veterinary research — size-adjusted for dogs (small/medium/large/giant) and cat-specific lifecycle curves. The old 'multiply by 7' rule is inaccurate; this tool uses the AAHA and 2019 UCSD epigenetic clock formulas.

Pet age (years)

Size

20–50 lb (9–23 kg) — Beagle, Border Collie

In human years

Adult

Rough estimate. Individual health depends on breed, diet, and veterinary care.

Frequently Asked Questions

References

AAHA Canine Life Stage Guidelines — American Animal Hospital Association
Quantitative translation of dog-to-human aging by epigenetic clocks — Cell Systems (UCSD, 2020)

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Frequently Asked Questions

References and sources

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