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PetAge

Dog age calculator

Enter age and adult size class. You’ll get an epigenetic estimate (Wang 2020) and a size-chart estimate (veterinary handbook table via AAHA poster), plus the folklore 7× number for contrast.

Sources: Wang et al. 2020 (doi) · AAHA physiological-age poster · sources

How the dog-age model works

The epigenetic line uses Wang et al. (Cell Systems, 2020): human_age = 16 × ln(dog_age) + 31 with dog age in years and natural log. That fit came primarily from Labrador retriever methylation data; we surface it as an estimate, not a breed-universal constant. Parallel to that, the size-chart path looks up human-equivalent years on the AAHA physiological-age poster (adapted from Eldredge et al., Dog Owner’s Home Veterinary Handbook). Poster weight bands are small ≤20 lb, medium 21–50 lb, large 51–90 lb, and giant >90 lb. Years 1–2 are 15 then 24 human-equivalent across sizes; from year 3 the poster diverges by band.

What the output range means

You should expect two numbers that often disagree. Wang’s curve is continuous and methylation-based; the poster is a discrete veterinary-handbook table by size. Neither is a clinical diagnosis. The 7× myth line is shown only so you can see how far folklore sits from both published methods.

Limits (read before sharing the result)

  • Wang’s training skew toward Labradors — other breeds may age differently.
  • Ages under ~0.1 year are early-life estimates; zero age is refused.
  • Ages above 30 years return an error rather than an invented extrapolation.
  • Size class is adult expected weight, not current puppy weight.
  • AAHA’s 2019 Canine Life Stage Guidelines prefer life stages over human-year conversion for care planning.

When to consult a veterinarian

Talk to a vet for vaccination schedules, senior screening, pain, weight loss, or breed-specific disease risk. This page does not replace a physical exam. If your dog is ill, underweight, or a giant breed with known orthopedic risk, use clinical judgment — not a human-year conversion — to decide next steps.

Dog age FAQ

Is one dog year equal to seven human years?
No. The 7× rule is folklore. Wang et al. (2020) use a logarithmic epigenetic mapping instead.
Where do the size-chart ages come from?
AAHA physiological-age poster values adapted from Eldredge et al.’s veterinary handbook appendix.
Why two human-year estimates?
Epigenetic (Wang) and size-chart (AAHA poster) answer different questions; disagreement is expected and disclosed.
When should I ignore this and call a vet?
For care decisions, prefer AAHA life stages and a clinical exam — especially for sick, underweight, or giant-breed dogs.