Free calculator
Dog age calculator
A 5-year-old dog is about 39 in human years by the AKC rule and about 57 by the epigenetic clock. Enter your dog's or cat's age in years and months to see both, and why the old "multiply by seven" is wrong.
Result
- Human years (AKC rule: 15, 9, then 5 a year)
- 39 years
- Human years (epigenetic clock, 16 ln(age) + 31)
- 57 years
Two published ways to say it. The AKC rule fits a medium-sized dog; small breeds age slower after year two and giant breeds faster. The epigenetic clock (UC San Diego, DNA methylation in Labradors) front-loads ageing: a 1-year-old dog is already about 31 in human terms.
How it works
The American Kennel Club guideline for a medium-sized dog: the first year counts as 15 human years, the second as 9, and every year after that as 5. That gives 39 at five and 64 at ten. Small breeds age slower after year two and giant breeds faster, which is why the AVMA calls small dogs senior at 7 and large dogs as early as 5 or 6.
In 2019-2020, researchers at UC San Diego compared DNA methylation in 104 Labradors with the human epigenetic clock and published a formula: human age = 16 x ln(dog age) + 31. It front-loads ageing: a 1-year-old dog maps to about 31, a 5-year-old to 57, a 10-year-old to 68. It applies to dogs one year and older and was measured in one breed, so it is a second opinion, not a replacement for the rule.
For cats, the International Cat Care chart counts the first two years as 24 human years and 4 for every year after, so a 10-year-old cat is 56. None of these is biology in the strict sense; they are conventions that make life-stage advice (kitten, junior, adult, mature, senior) easier to picture.
Frequently asked questions
- How old is my dog in human years?
- AKC rule: 15 at one, 24 at two, then add 5 a year (39 at five, 64 at ten). Epigenetic clock: 31 at one, 57 at five, 68 at ten. Enter years and months above for your dog.
- Is one dog year really seven human years?
- No. The seven-year rule ignores that dogs mature fast early and slow down later: a 1-year-old dog can breed, which no 7-year-old child can. Both published methods give 39-57 human years for a 5-year-old dog, not 35.
- When is a dog considered senior?
- The AVMA puts small dogs and cats at senior from about 7 years old, and large or giant breeds from 5 or 6. Size matters more than the conversion formula: large dogs age faster.
- How old is my cat in human years?
- International Cat Care: 15 at one year, 24 at two, then 4 a year: 36 at five, 56 at ten, 76 at fifteen. Switch the calculator to Cat for any age.
Guides
- How old is my dog in human years? Table from 1 to 16
Year-by-year table of dog age in human years by the AKC rule and the epigenetic clock, when a dog is senior by size, and the International Cat Care cat table.