Dog Age Calculator
Dogs do not age "7 years for every 1". In the common guideline the first year equals about 15 human years and the second about 9 more. After that, our chart sets the pace by size. Enter age and size to see the estimate.
Last reviewed
A chart-based estimate. Individual aging depends on breed, weight and health.
The chart we use
year 1 = 15 human years · year 2 = 24 · then: small +4, medium +5, large +6 per year The medium-dog schedule is the widely published guideline that the American Kennel Club attributes to the American Veterinary Medical Association: 15 human years for the first year, about nine for the second, and approximately five for each year after that. For small and large dogs we use 4 and 6 per year. That part is our own approximation, based on the finding that larger dogs age faster. The AVMA's current page for pet owners does not publish a conversion table; it says that "dogs do not age at a rate of 7 human years per dog year." Sources are listed below and in the Methodology.
Dog age chart in human years, by size
The same numbers as the calculator, for whole years. Small means under 22 lb, medium 22 to 55 lb, large over 55 lb (adult weight).
| Dog's age | Small dog | Medium dog | Large dog |
|---|---|---|---|
| 1 year | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 |
| 3 years | 28 | 29 | 30 |
| 4 years | 32 | 34 | 36 |
| 5 years | 36 | 39 | 42 |
| 6 years | 40 | 44 | 48 |
| 7 years | 44 | 49 | 54 |
| 8 years | 48 | 54 | 60 |
| 9 years | 52 | 59 | 66 |
| 10 years | 56 | 64 | 72 |
| 11 years | 60 | 69 | 78 |
| 12 years | 64 | 74 | 84 |
| 13 years | 68 | 79 | 90 |
| 14 years | 72 | 84 | 96 |
| 15 years | 76 | 89 | 102 |
| 16 years | 80 | 94 | 108 |
Human years, rounded. Estimates, not a diagnosis of your dog's health.
Why big dogs age faster
Across mammals, bigger species usually live longer. Within dogs it is the other way round. The AVMA notes that "larger breed dogs tend to have shorter life spans than smaller breeds." A study in The American Naturalist fitted mortality models to death data from 74 breeds of dogs and concluded: "large dogs die young mainly because they age quickly." That is the reason a size setting changes the result here, and the reason a single multiplier cannot fit every dog.
When is a dog a senior?
There is no single age. The AVMA says experts suggest that dogs be considered senior "when they reach the last 25 percent of the estimated life span for their breed." On average, using data from the American Kennel Club, it lists these ages:
- Small or toy breeds (less than 20 pounds): 8 to 11 years
- Medium-sized breeds (20 to 50 pounds): 8 to 10 years
- Large breeds (50 to 90 pounds): 8 to 9 years
- Giant breeds (more than 90 pounds): 6 to 7 years
The AVMA's weight bands differ slightly from the three sizes in this calculator, and it adds a giant group. For older dogs it advises more vet care: "Senior pets need to see a veterinarian twice a year or more."
The DNA formula: 16 x ln(age) + 31
In 2020 researchers compared DNA methylation in dogs and humans and published the
function human_age = 16 ln(dog_age) + 31 (Wang and
colleagues, Cell Systems). By that formula a dog of 1 year is about 31, 2 years is about 42, 5 years is about 57 and 10 years is about 68 in human years.
The study characterized the methylomes of "104 Labrador retrievers spanning a 16-year age range." Because the dogs were mainly Labrador retrievers, we do not use it for a calculator that has to work for a Chihuahua and a Great Dane alike.
Adopted a dog and do not know its age?
For a young dog, the teeth give a rough clue. The Merck Veterinary Manual says dogs "have 28 baby teeth that fall out and are replaced by 42 adult teeth. This happens between 2 and 7 months of age." A dog that is still changing teeth is probably between about 2 and 7 months old, though individual dogs vary. For an adult dog there is no reliable home method in our sources: ask your veterinarian for an estimate at the first checkup, then use it here.
Entering a new life stage?
When the stage changes (puppy, adult, senior), the portions change too. Get the new daily amount with the dog food calculator →
Sources
- American Veterinary Medical Association: Caring for senior cats and dogs (senior ages by size, vet visits, the 7-year rule)
- American Kennel Club: How to Calculate Dog Years to Human Years (the 15, 9 and 5 guideline, which the AKC attributes to the AVMA)
- Kraus C, Pavard S, Promislow DEL. The size-life span trade-off decomposed: why large dogs die young. The American Naturalist, 2013.
- Wang T and colleagues. Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome. Cell Systems, 2020.
- Merck Veterinary Manual: Description and Physical Characteristics of Dogs (teeth)
Frequently asked questions
Is the "1 dog year = 7 human years" rule true?
No. The American Veterinary Medical Association says that dogs do not age at a rate of 7 human years per dog year. Dogs mature fast early on: in the common guideline, published by the AKC, which attributes it to the AVMA, the first year of a medium dog equals about 15 human years and the second adds about 9. After that our chart adds 4 to 6 human years per year, depending on size.
How old is a 10 year old dog in human years?
In our chart a 10 year old dog is about 56 in human years if it is small, 64 if it is medium and 72 if it is large. These are estimates: individual aging depends on breed, weight and health.
Why does my dog's size matter?
Larger dogs age faster. A study of death data from 74 breeds concluded that large dogs die young mainly because they age quickly. That is why the chart gives size its own setting. The 4, 5 and 6 human years per year are our own approximation of that effect, not figures from the study.
When does my dog become a senior?
It varies with size. The AVMA lists, on average, 8 to 11 years for small or toy breeds (less than 20 pounds), 8 to 10 years for medium-sized breeds (20 to 50 pounds), 8 to 9 years for large breeds (50 to 90 pounds) and 6 to 7 years for giant breeds (more than 90 pounds). It also says senior pets need to see a veterinarian twice a year or more.
What about the logarithm formula that made headlines?
The formula human_age = 16 x ln(dog_age) + 31 comes from a 2020 study of DNA methylation in 104 dogs, mainly Labrador retrievers. It was built mainly on one breed, so we do not apply it to every dog. The size-based chart is an estimate that works for any dog.