Dog years calculator
Your dog's age in human years, from the published epigenetic clock rather than the seven times rule that nobody has ever been able to source. The formula, its sample and its limits are all on this page.
An age in human years is a conversation starter, not a diagnosis. What actually matters is what changes with age: how often your dog is seen, what gets screened for, what it is fed and how much it moves. Your vet decides all four.
The formula
human age = 16 * ln(age_years) + 31
The clock was built from targeted DNA methylation sequencing of 104 Labrador Retrievers, 95 after quality filtering, aged 0.1 to 16 years. The authors state that their study focused exclusively on Labrador Retrievers and that distinct breeds with widely varying lifespans could yield different epigenetic age translation functions. It is a single breed result, so treat the number as a well grounded estimate rather than a measurement of your own dog. Below about 7.5 weeks of age the expression returns a negative number, which is arithmetic rather than a finding, so Puplr does not apply it under 0.15 years. The published version sits behind cell.com, which refused automated access, so the wording above was read from the authors' own full text preprint.
From Wang et al. 2020, Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome, Cell Systems 11(2):176-185. Read it.
The first year
The logarithmic formula is anchored on adult ageing and gives an odd answer for a very young puppy: at exactly 1 year it returns 31 human years, and it falls apart below about 7.5 weeks. The paper itself gives one sourced milestone for puppies. It aligns roughly 8 weeks in a dog, 0.15 years, with roughly 9 months in a human, 0.78 years, because that is when deciduous teeth erupt in both species. At the other end it notes that the 12 year expected lifespan of a Labrador Retriever translates to the worldwide human life expectancy of 70 years. Puplr publishes those two anchors and nothing else for the first year. The commonly repeated line that a 6 month old puppy is like a 10 year old child could not be traced to any veterinary or peer reviewed source in this pass, so it is not on the site.
The one veterinary table we could source
This is the only dog age to human age table Puplr could source from a veterinary body. It is not size specific. The AVMA footnotes it: "Based on a medium-sized dog weighing 21-50lbs. Many other factors, including weight and breed, may influence the aging process." It also says pet ages are approximate calculations. It is published for medium dogs only, so Puplr shows it as a single column rather than pretending it covers four size classes.
| Dog age | Human age |
|---|---|
| 1 | 15 |
| 2 | 24 |
| 3 | 28 |
| 4 | 32 |
| 5 | 36 |
| 6 | 42 |
| 7 | 47 |
| 8 | 51 |
| 9 | 56 |
| 10 | 60 |
| 11 | 65 |
| 12 | 69 |
| 13 | 74 |
| 14 | 78 |
| 15 | 83 |
| 16 | 87 |
From AVMA, Pets Age Faster Than People client handout. Source.
When a dog counts as senior
This is where size genuinely matters, and it is the part worth acting on: a senior dog usually moves to twice yearly check ups and gets screened for things a young adult is not.
| Size | Senior from | What the source says |
|---|---|---|
| Small, under 9 kg or 20 lb | 7 years | The AVMA says cats and small dogs are generally considered senior at seven years old, while adding that they have plenty of life left at that age. Source |
| Medium, 9 to 23 kg or 21 to 50 lb | Not published | No senior age for medium dogs specifically could be sourced. The AVMA statement splits dogs into small and larger breeds and gives no middle figure. The AVMA age chart Puplr uses is built on a medium dog of 21 to 50 lb, so the size band itself is sourced even though the senior age is not. Source |
| Large, 23 to 45 kg or 51 to 100 lb | 5 years | The AVMA says larger breed dogs tend to have shorter lifespans than smaller breeds and are often considered senior when they are 5 to 6 years of age. Puplr uses the earlier end of that range. Source |
| Giant, over 45 kg or 100 lb | 5 years | The AVMA statement recognises only small dogs and larger breed dogs, so this figure is the larger breed one repeated. No source reached in this pass gives giant breeds a separate senior age, and Puplr is not going to invent one. Source |
Life stages
The AAHA task force declined to publish human age equivalents at all. Verbatim: "For practical purposes, rather than attempt to calculate age equivalents to humans, the task force suggests that life stage be defined both by age and characteristics". It also notes that estimates of inclusive ages are not uniform and therefore are not proposed for the mature adult and senior stages.
| Stage | Definition |
|---|---|
| Puppy | Birth to cessation of rapid growth, about 6 to 9 months, varying with breed and size |
| Young adult | Cessation of rapid growth to completion of physical and social maturation, which occurs in most dogs by 3 to 4 years of age |
| Mature adult | Completion of physical and social maturation until the last 25 percent of estimated lifespan, breed and size dependent |
| Senior | The last 25 percent of estimated lifespan through end of life |
| End of life | Terminal stage, depends on the specific pathologies |
From 2019 AAHA Canine Life Stage Guidelines, Table 1. Source.
Common questions
Is one dog year really seven human years?
No. The AVMA is blunt about it: "Contrary to popular belief, dogs do not age at a rate of 7 human years for each year in dog years." Dogs age fastest in their first two years and then slow down, so a straight multiplier gets the shape of the curve wrong at both ends. The American Kennel Club records that one explanation for the seven year rule is that people lived to about 70 and dogs to about 10, and quotes a veterinarian calling it a marketing ploy to get owners in for annual check ups.
What is the science backed formula?
Human age = 16 x ln(dog age in years) + 31, from a 2020 epigenetic clock study in Cell Systems. The researchers sequenced DNA methylation at targeted sites in 104 Labrador Retrievers spanning 0.1 to 16 years and matched the pattern of change against human methylation data. On that formula a 1 year old dog lands at 31, a 2 year old at about 42 and a 5 year old at about 57.
Does it work for my breed?
Not exactly. The study used a single breed, Labrador Retrievers, and the authors say plainly that breeds with widely varying lifespans could yield different translation functions. A Chihuahua and a Great Dane do not age at the same rate, and the formula has no size input at all. Treat it as a good estimate with a wide margin, not a reading of your own dog.
When is my dog a senior?
AAHA defines senior as the last 25 percent of estimated lifespan through end of life, which means the answer depends on how long your dog's breed is expected to live rather than on a fixed birthday. As a rough guide the AVMA says small dogs are generally considered senior at seven, while larger breeds are often considered senior at 5 to 6. The 2023 AAHA Senior Care Guidelines put it this way: because of the variability in ageing based on species and breed, there is no specific age for senior status.
Why does Puplr not show a table by size?
Because no veterinary body publishes one that could be verified. The AVMA table on this page covers a medium dog of 21 to 50 lb and says so. AAHA deliberately declined to publish human age equivalents at all. Size specific charts are everywhere online, but every version reached in this pass either had no source or traced back to another chart with no source, so Puplr does not print one.
What is my puppy's human age?
For the first year the honest answer is that nobody publishes a reliable conversion. The one sourced milestone is from the epigenetic study: roughly 8 weeks in a puppy lines up with roughly 9 months in a human infant, because that is when the baby teeth come in for both. After 12 months the formula gives sensible numbers and the AVMA table gives 15 human years for the first year of a medium dog.
Where the sources disagree
- No size specific human age table could be sourced, so Puplr publishes none. The AVMA table is medium dogs only and says so in its own footnote. AAHA went further and refused to publish equivalents at all: "For practical purposes, rather than attempt to calculate age equivalents to humans, the task force suggests that life stage be defined both by age and characteristics." Every size specific chart found online either carried no source or pointed at another chart with no source.
- The epigenetic formula and the AVMA table do not agree. At 1 year the formula gives 31 human years, the AVMA table gives 15. At 12 years the formula gives about 71, the AVMA table gives 69. They converge in old age and diverge badly in youth, because the formula is fitted to methylation across the whole life course while the AVMA table is a client education aid.
- Senior age is defined two different ways. AAHA uses a proportion of expected lifespan, the last 25 percent, which moves with the breed. The AVMA uses fixed ages, about 7 for small dogs and 5 to 6 for larger breeds. Both are on this page because both are in wide clinical use.
- AAHA 2019 gives inclusive ages for the puppy and young adult stages only. Verbatim: "Because variation increases toward the latter years, estimates of inclusive ages are not uniform and therefore are not proposed for the life stages of mature adults and seniors." So the senior boundary is deliberately left to the vet.
- The Wang study is single breed. Its own limitations section says distinct breeds exhibiting widely varying lifespans could yield different epigenetic age translation functions, which is the exact weakness of every size free conversion including this one.
- UK VetCompass life tables give an overall life expectancy at birth of 11.23 years across 30,563 deceased dogs, but the paper does not stratify by body size, so it cannot be used to build a size specific senior threshold either.
Next
Sources
- Wang et al. 2020, Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome, authors' full text: https://www.biorxiv.org/content/10.1101/829192v2.full
- Published version, Cell Systems 11(2):176-185, blocked automated access with HTTP 403: https://www.cell.com/cell-systems/fulltext/S2405-4712(20)30203-9
- American Kennel Club, how to calculate dog years to human years, which quotes the AVMA position in full: https://www.akc.org/expert-advice/health/how-to-calculate-dog-years-to-human-years/
- AVMA, Pets Age Faster Than People client handout, dog and cat age tables: https://ebusiness.avma.org/files/productdownloads/PetsAgeFaster.pdf
- 2019 AAHA Canine Life Stage Guidelines, J Am Anim Hosp Assoc 2019; 55:267-290: https://www.aaha.org/wp-content/uploads/globalassets/02-guidelines/canine-life-stage-2019/2019-aaha-canine-life-stage-guidelines-final.pdf
- 2023 AAHA Senior Care Guidelines for Dogs and Cats, J Am Anim Hosp Assoc 2023; 59:1-21: https://www.aaha.org/wp-content/uploads/globalassets/02-guidelines/2023-aaha-senior-care-guidelines-for-dogs-and-cats/resources/2023-aaha-senior-care-guidelines-for-dogs-and-cats.pdf
- American Kennel Club size bands used for growth and ageing: https://www.akc.org/expert-advice/health/when-does-my-puppy-finish-growing/
- Teng et al. 2022, Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom, Scientific Reports: https://pmc.ncbi.nlm.nih.gov/articles/PMC9050668/
Last reviewed 2026-09-06.