Dog Age Calculator: Dog Years to Human Years
Convert your dog's age in years and months to human years with a size chart for small, medium, large and giant dogs, or the 2019 epigenetic clock formula. Also works for cats.
Enter the age in years and months to see it in human years.
About the Dog Age Calculator
The Dog Age Calculator turns your dog's age into human years, so you can picture where your dog is in life: a bouncy teenager, an adult in its prime, or a senior that needs a gentler routine. Type the age in years and months, choose your dog's adult size, and the human age appears at once. The page shows two methods side by side, names each one, and says when a result is only approximate. Choose Cat to switch to the Cat Age Calculator rule instead.
The old rule of seven human years for every dog year is a myth. Dogs grow up very fast in their first two years and then age more slowly, and big dogs age faster than small ones in later life. The results here are estimates, not a health assessment.
How to use it
Steps
- Leave Pet on Dog.
- Type the Years and Months. Either can be left empty, which counts as zero.
- Choose the Adult size: small (up to 20 lb), medium (21 to 50 lb), large (51 to 100 lb) or giant (over 100 lb).
- Pick the Method. The size chart is the default; the epigenetic clock is offered from one year.
The size chart
The default method uses the typical published values of the widely shared AVMA-style dog age chart. It gives a human age at each whole dog year from 1 to 16, by size. A one-year-old dog is 15 in human years (12 for giant breeds), and a two-year-old is 24 (22 for giants). Between whole years the calculator draws a straight line, and from birth to the first birthday it starts at zero. Past 16 years it adds the chart's last yearly step for each extra year and says so. Because published versions of the chart differ by a year or two in places, the figures are kept in one table that is easy to check and correct.
The epigenetic clock
In 2019 Wang and colleagues compared chemical marks on the DNA of Labrador retrievers and people, and published a formula in Cell Systems:
It gives 31 at one year, 42.1 at two, 53.2 at four and 67.8 at ten. It was fitted on adult dogs and goes negative close to birth, so the calculator offers it only from one year.
Worked examples
- A medium dog of 5 years and 6 months: halfway between 36 and 42, so 39.
- A medium puppy of 6 months: half of 15, so 7.5.
- A large dog of 18 years: 99 at 16, plus two steps of 6, so 111.
For people, the Age Calculator gives an exact age in years, months and days, and the Days Until Calculator counts down to your dog's next birthday.
Privacy
Nothing is uploaded; every calculation runs in your browser and never leaves your device. The ages you type stay on this page and are gone when you close or reload it.
Frequently asked questions
Is one dog year really seven human years?
No. Dogs mature much faster at the start: a one-year-old dog is roughly like a 15-year-old person, and a two-year-old like a 24-year-old. After that, each dog year counts for about 4 to 7 human years, depending on size.
Why does my dog's size matter?
Large and giant breeds age faster in later life than small dogs. On the size chart a 10-year-old small dog is about 56 in human years, while a 10-year-old large dog is about 66.
What is the epigenetic clock formula?
Researchers led by Wang compared DNA methylation in Labrador retrievers and people and published human age = 16 ln(dog age) + 31 in Cell Systems in 2019. It was fitted on adult dogs, so the calculator offers it from one year.
Where do the size chart figures come from?
They are the typical values of the widely shared AVMA-style dog age chart. Published versions differ by a year or two in places, so treat the result as an estimate rather than an exact age.
Can I work out my cat's age too?
Yes. Choose Cat and the calculator uses the AAHA and AAFP style rule: 15 human years at one, 24 at two, and 4 more for each year after that. Size does not apply to cats.