Dog Age Calculator — Dog Years to Human Years
Convert your dog's age to human years using a size-adjusted model and the 2019 epigenetic-clock formula.
A medium dog is expected to live about 12.7 years (Montoya et al., Frontiers in Veterinary Science, 2023 — millions of dogs in American clinics). It is an average: a dog past it shows over 100%.
Human age (AVMA) follows the vet chart: 15 for the first year, 9 for the second, then 4–7 a year by size. Epigenetic estimate is the formula from the 2019 DNA-methylation study, 16 × ln(age) + 31, which ages a young dog faster and an old dog slower — so the two numbers differ.
Where the two models cross: Small 14.4 yrs (73.7 human) · Medium 11.1 yrs (69.5 human) · Large 9 yrs (66.2 human) · Giant 7.7 yrs (63.6 human). Younger than this, the epigenetic estimate is the older of the two; past it, the chart is.
What helps at this stage: A wellness exam at least once a year, with an eye on weight and teeth — the two things that most often slip in the middle years.
Dog age chart — human years by size
| Dog age | Small | Medium | Large | Giant | Epigenetic estimate |
|---|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 15 | 31 |
| 2 | 24 | 24 | 24 | 24 | 42.1 |
| 3 | 28 | 29 | 30 | 31 | 48.6 |
| 4 | 32 | 34 | 36 | 38 | 53.2 |
| 5 | 36 | 39 | 42 | 45 | 56.8 |
| 6 | 40 | 44 | 48 | 52 | 59.7 |
| 7 | 44 | 49 | 54 | 59 | 62.1 |
| 8 | 48 | 54 | 60 | 66 | 64.3 |
| 9 | 52 | 59 | 66 | 73 | 66.2 |
| 10 | 56 | 64 | 72 | 80 | 67.8 |
| 11 | 60 | 69 | 78 | 87 | 69.4 |
| 12 | 64 | 74 | 84 | 94 | 70.8 |
| 13 | 68 | 79 | 90 | 101 | 72 |
| 14 | 72 | 84 | 96 | 108 | 73.2 |
| 15 | 76 | 89 | 102 | 115 | 74.3 |
| 16 | 80 | 94 | 108 | 122 | 75.4 |
Age not known? What the teeth say
Rough guidelines for a dog adopted as an adult. Every dog and breed is different, diet and dental care change the picture — a professionally cleaned mouth looks younger — and a vet’s examination narrows it further, though never to a birthday.
| About | Teeth |
|---|---|
| 8 weeks | Puppy teeth are all in. |
| 7 months | Adult teeth are all in, white and clean. |
| 1–2 years | Teeth begin to look dull and may be yellowing. |
| 3–5 years | Tartar build-up and wear. |
| 5–10 years | More wear, and possibly signs of disease. |
| 10–15 years | Heavily worn; some may be missing. |
🔒 Calculated in your browser. Two common models — a size-adjusted AVMA-style estimate and the 2019 epigenetic-clock formula. Approximations, not veterinary advice.
Your dog’s age in human years
The old "multiply by 7" rule is a myth — dogs mature fast early on, then age more slowly, and larger breeds age quicker. Enter your dog’s age and size and the tool gives a size-adjusted estimate (first year ≈ 15, second ≈ +9, then per-year by size) alongside the 2019 epigenetic-clock formula (16 × ln(age) + 31).
Two models, both estimates
The size-adjusted model is the familiar vet-style guide; the epigenetic formula comes from a DNA-methylation study on Labradors and skews older for young dogs. Both are approximations — real ageing varies by breed and health. Adopted a grown dog and do not know its age? “Age not known? What the teeth say” lists what the teeth look like at each age, from a full set of puppy teeth to heavily worn ones, with the caveats that keep it a rough guide. Everything runs in your browser.
Frequently asked questions
Is one dog year seven human years?
No — that’s a myth. A dog’s first year is roughly 15 human years and the second about 9 more, then it slows and depends on size. The "Dog age chart" under the result lists the human age for every size, year by year.
Why do bigger dogs age faster?
Larger breeds have shorter lifespans and reach "senior" age sooner, so the tool adds more human years per dog year for large dogs than small ones.
What life stage is my dog in?
The "Life stage" figure beside the two ages says: Puppy in the first year, Adolescent in the second, then Adult until the age its size turns senior, Senior, and Geriatric after that — bigger dogs reach each stage sooner.
How long is my dog expected to live, and how far along is it?
The “Of expected life” figure divides your dog's age by the life expectancy for its size, and the line under it names that expectancy and where it comes from: Montoya et al. in Frontiers in Veterinary Science, the largest study that gives a figure for every size, giant included. It is an average over millions of dogs, so a healthy dog can outlive it — past it the figure reads over 100%.
Where do the two models agree, and what helps at my dog's age?
“Where the two models cross” gives, for every size, the dog age where the size-adjusted chart overtakes the epigenetic estimate: younger than that the epigenetic figure is the older of the two, past it the chart is, and bigger dogs reach it sooner. “What helps at this stage” adds a line of general care for the life stage — from vaccinations and socialising for a puppy to telling the vet early about changes in a geriatric dog — which is not a diagnosis.
Can it estimate the age of a dog whose birthday I don't know?
Roughly. “Age not known? What the teeth say” lists what a dog's teeth look like at each age, from a full set of puppy teeth, through clean white adult teeth and the first dullness, tartar and wear, to heavily worn and missing teeth in old age. Every dog and breed differs, a professionally cleaned mouth looks younger, and a vet's examination narrows it further but never to a birthday — use it for an age band, then enter that age above.