Dog Age Calculator: Dog Years to Human Years
The old “one dog year equals seven human years” rule is wrong in both directions. Dogs grow up far faster than that in their first two years, then age more slowly. Enter your dog’s age below to get two better estimates of your dog’s age in human years, plus the life stage vets would put your dog in.
How the calculator works
The AVMA age chart
The first number comes from the American Veterinary Medical Association’s “Pets age faster than people” chart. It is based on a medium-size dog weighing 21 to 50 pounds. A 1-year-old dog is about 15 in human terms, a 2-year-old about 24, and from there each year adds roughly four to five human years. For ages between whole years, the calculator fills in the gap in a straight line.
The DNA-based formula
The second number comes from a 2020 study by researchers at the University of California San Diego, published in Cell Systems. They compared age-related chemical changes to DNA, called methylation, in people and in Labrador retrievers. Their formula is human age = 16 × ln(dog age) + 31, where ln is the natural logarithm. By this measure dogs age very fast at first: a 1-year-old Labrador is comparable to a 31-year-old person. After that their aging slows down. The study only used Labradors, aged from a few weeks to 16 years. Treat this number as a second opinion rather than a precise answer for every breed.
Dog years to human years chart
| Dog’s age | AVMA chart (medium dog) | DNA formula |
|---|---|---|
| 1 year | 15 | 31 |
| 2 years | 24 | 42 |
| 3 years | 28 | 49 |
| 4 years | 32 | 53 |
| 5 years | 36 | 57 |
| 6 years | 42 | 60 |
| 7 years | 47 | 62 |
| 8 years | 51 | 64 |
| 9 years | 56 | 66 |
| 10 years | 60 | 68 |
| 12 years | 69 | 71 |
| 14 years | 78 | 73 |
| 16 years | 87 | 75 |
Size matters too. Small dogs generally live longer and age more slowly once they are grown, while large and giant breeds age faster. AVMA’s size-based figures put a 10-year-old dog anywhere from the mid-50s for a small dog to the late 70s for a giant breed in human terms. A 10-year-old Chihuahua and a 10-year-old Great Dane are in very different places.
Dog life stages
Instead of converting to human years, vets now think in life stages. The 2019 AAHA Canine Life Stage Guidelines describe five:
- Puppy: from birth until rapid growth ends, around 6–9 months of age.
- Young adult: until the dog is physically and socially mature, around 3–4 years.
- Mature adult: from then until the last quarter of the expected lifespan.
- Senior: the last 25% of the expected lifespan, which depends on breed and size.
- End of life: the final stage, which can come at any age.
Because “senior” depends on how long dogs of that breed and size usually live, ask your vet when to start senior checkups. Our guides to caring for a senior dog and how much to feed your dog cover what changes as dogs get older.
Common questions
Is one dog year really seven human years?
No. The seven-year rule makes young dogs look too young and old dogs too old. A 1-year-old dog is a young adult in many ways, not the equivalent of a 7-year-old child.
Why do the two estimates differ so much?
They measure different things. The AVMA chart is a practical rule built around development and typical lifespan for a medium-size dog. The DNA formula tracks chemical changes in the genome and shows aging front-loaded into the first years. Both agree that dogs mature very quickly. They disagree mostly about middle age.
Which number should I use?
Either is fine for curiosity. For decisions about food, exercise and how often to see the vet, the life stage is more useful than the exact number.