Vicaya
More subjects

Updated

Dog age calculator

By VicayaGlobal Calculator Editorial Team

34 human yearsSee full result

Two answers, because there are two honest ways to convert dog years: the size rule vets have used for decades, and the 2020 DNA-methylation study that found dogs age fast early and slowly later. The size rule is the everyday answer; the study is the biological one, and it applies from one year old.

DogCat age calculator

For a puppy, enter 0 years and the months.

34 human years

Life stage: mature adult. A medium dog counts as senior from 9 years.

Size rule (AVMA): 15 for year one, +9 for year two, then +5 a year for a medium dog
34 human years
Study estimate: 16 ln(age) + 31 (Wang et al. 2020, Labrador-derived)
53.18 human years
Life stage (AAHA 2019)
mature adult
Senior from
9 years for a medium dog: twice-yearly exams, weight and dental checks from then on

What this means

The two numbers differ most for young dogs. The study says a one-year-old dog is already about 31 in human terms, because early development is fast; the size rule says 15. From middle age on they converge, and by eight years a medium dog is 54 by the rule and 64 by the study.

Size matters after the second year. Giant breeds age faster than small ones — about seven human years for every dog year against four — which is why the rule asks for adult size rather than breed.

Senior is a size question too: 11 years for a small dog, 9 for medium, 7 for large and 5 for giant breeds, taking the lower bound of the AAHA range for each.

Dog age chart: dog years to human years

The size rule above for every age from 1 to 16, in human years. Find your dog’s age in the first column and its adult size across the top.

Dog age chart: dog years to human years
Dog yearsSmallMediumLargeGiant
115151515
224242424
328293031
432343638
536394245
640444852
744495459
848546066
952596673
1056647280
1160697887
1264748494
13687990101
14728496108
157689102115
168094108122

When to see a vet

Formula and sources

Sources reviewed 18 September 2026. Each names the figure it supports.

This page is an educational estimate, not veterinary advice.

Frequently asked questions

Can I use this as a canine age calculator?

Use this canine age calculator to convert dog years to human years by adult size. Enter age in dog years using years and months; the dog age chart below lets you compare the size groups. Both estimates are educational conventions rather than a medical assessment.

How old is my dog in human years?

Use the size rule above: about 15 human years for the first dog year, 9 for the second, then 4 to 7 a year depending on size. A 4-year-old medium dog is about 34; the same dog is 53 by the 2020 study formula.

Is one dog year seven human years?

No. The "times seven" rule assumes dogs age evenly, and they do not: a one-year-old dog is sexually mature, which a seven-year-old child is not. Both methods here front-load the early years and slow down later.

When is a dog a senior?

It depends on size: from about 11 years for small dogs, 9 for medium, 7 for large and 5 for giant breeds, following the AAHA canine life-stage guidelines. From then on, twice-yearly check-ups.

What is the 16 ln(age) + 31 formula?

A 2020 study of DNA methylation in Labrador retrievers (Wang et al., Cell Systems) found dog and human ages line up on a logarithmic curve: human age = 16 × the natural log of the dog’s age + 31. It was fitted to dogs of one year and older, so this page does not apply it to puppies.

Can I enter my puppy’s age in months?

Yes: enter 0 years and the months. Under one year the size rule is stretched in proportion to the first-year figure of 15, and the result is labelled interpolated, because the rule itself only speaks in whole years.