Tool + Guide

Dog Age Calculator (Dog Years → Human Years) with Size/Breed Curves

Backed by modern research and practical charts. Get a free, downloadable birthday card with your dog’s photo and an age badge—then turn it into a keepsake portrait.

Why “1 dog year = 7 human years” is wrong

Dogs don’t age linearly. In 2019, researchers modeling an epigenetic clock (DNA methylation) proposed a logarithmic conversion: human age ≈ 16·ln(dog age) + 31 (age in years). That’s why a 2-year-old dog looks “middle-aged” in human terms, while aging slows thereafter.

Size and breed also matter. Small dogs generally live longer and age more slowly than large and giant breeds—so good calculators let you apply different curves or life-stage definitions by size. Veterinary bodies emphasize tailoring care by life stage, size, lifestyle, and breed.

Dog Age Calculator

Size / weight class (choose one)
Model

Notes: The UCSD model was derived primarily from Labrador retrievers and reflects biological (epigenetic) age. Size curves are approximate heuristics commonly used in pet care charts; individual dogs vary.

Birthday Card Generator

Tip: Use a centered head-and-shoulders photo. The generator creates a social-ready PNG (1080×1350).

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We avoid listing prices here to keep this guide evergreen—see product pages for current options.

FAQ

Is the 1:7 rule accurate?

No. The UCSD epigenetic model shows a fast early ramp and a slower curve later: human age ≈ 16·ln(dog age) + 31.

Which should I use—epigenetic model or size curve?

Use epigenetic for a science-based, breed-agnostic estimate; use size curve when you want the practical reality that small dogs age more slowly than giant breeds. Try both to see the range.

Why do larger dogs age faster?

Physiology and life-history differences mean large/giant breeds hit life stages earlier and carry higher age-related risks—hence separate charts and earlier senior care.

How were the size curves set here?

They’re a simplified blend of common veterinary charts: ~15 human years at 1 dog year, ~24 at 2, then annual add-ons that differ by size (small < medium < large < giant). Exact numbers vary across charts; use this as a guide, not a diagnosis.

Do breed genetics matter?

Yes. The UCSD research was anchored on Labradors, and life expectancy varies by breed. Use the calculator as an estimate and consult your vet for individualized care.

Sources: UC San Diego (Cell Systems epigenetic model), Smithsonian coverage, AKC guidance, and AAHA Canine Life Stage Guidelines.