Calculator
How old is my dog in human years?
Times seven is a myth. Enter your dog's age and size and the calculator uses the size adjusted table method, with the epigenetic formula alongside for comparison.
Roughly in human years
— years
size adjusted table method · —
Epigenetic formula
—
16 × ln(age) + 31 (Wang et al., 2020)
Dog years to human years by size
| Dog's age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 |
| 3 years | 28 | 29 | 30 | 31 |
| 4 years | 32 | 34 | 36 | 38 |
| 5 years | 36 | 39 | 42 | 45 |
| 6 years | 40 | 44 | 48 | 52 |
| 7 years | 44 | 49 | 54 | 59 |
| 8 years | 48 | 54 | 60 | 66 |
| 9 years | 52 | 59 | 66 | 73 |
| 10 years | 56 | 64 | 72 | 80 |
| 11 years | 60 | 69 | 78 | 87 |
| 12 years | 64 | 74 | 84 | 94 |
| 13 years | 68 | 79 | 90 | 101 |
| 14 years | 72 | 84 | 96 | 108 |
| 15 years | 76 | 89 | 102 | 115 |
| 16 years | 80 | 94 | 108 | 122 |
Why times seven does not work
The rule of seven came from simply dividing the average human lifespan by the average dog lifespan. It ignores the fact that a dog matures within a single year: a one year old dog is sexually mature and fully grown, which in a person corresponds to about fifteen years. After the second year the pace slows and depends mainly on size. A Chihuahua at ten is a fresh senior; a Great Dane at the same age is deeply geriatric.
Two methods, two views
The table method, used by the AVMA and breed clubs, is practical and matches how vets divide life stages. The epigenetic method from 2020 measures biological ageing at the level of DNA and shows that young dogs are older than the tables suggest, while ageing slows in seniors. For everyday decisions, such as when to switch to a senior food or increase vet visits, the table is more useful; treat the epigenetic formula as an interesting comparison.
What this means for feeding
Moving into old age is the main reason to track your dog's age at all. A senior needs less energy but more good quality protein to hold muscle, and often joint support. The portion calculator has a separate setting for seniors. For individual breeds you will find the age of seniority and the food composition to aim for in the breed profiles.
Common questions
How do you convert dog years to human years?
The old rule of one dog year to seven human years does not hold, because dogs mature far faster than people and then age more slowly. The practical method counts the first year as about 15 human years, adds 9 for the second (24 in total) and then adds 4 a year for small dogs, 5 for medium, 6 for large and 7 for giant breeds.
How much is one dog year?
It depends on the dog’s age and size. The first year of life is worth roughly 15 human years, the second about 9 and every year after that 4 to 7 depending on size. So one dog year is not a constant: for a five year old medium dog it works out at about 5 human years.
Why do large dogs age faster?
Large and giant breeds have a shorter average lifespan, around 7 to 10 years, than small breeds at 12 to 16. Rapid growth in youth, a heavier load on the heart and joints and a higher rate of some cancers shorten their lives, so each calendar year covers more human ageing.
What is the epigenetic dog age formula?
A 2020 study by Wang and colleagues in Cell Systems compared DNA methylation in Labradors and humans and derived the formula human age = 16 × ln(dog age) + 31. By that measure a one year old dog is around 31 and a four year old about 53. It reflects biological ageing of cells, but was built mainly on Labradors and gives unrealistically high numbers for puppies.
When is a dog a senior?
Small breeds around 10 years, medium around 8, large around 7 and giant breeds as early as 5 to 6. At that point it is worth moving to a senior food, running annual blood work and keeping an eye on joints, teeth and weight.
How long do mixed breed dogs live?
Mixed breeds tend to live slightly longer than purebred dogs of the same size, usually 12 to 15 years for smaller ones and 10 to 13 for larger. Size is what matters: a small mix ages like a small breed and a large one like a large breed. Pick the size by weight in the calculator.