Convert your dog's or cat's age into human years. Instead of the outdated "age × 7" formula, this calculator applies the standards used in veterinary medicine — the real growth curve where pets mature quickly early on and then age more gradually — and for dogs it also reflects the difference in aging speed by size.
Converted values are based on statistical averages. Depending on breed, genetics, health, and living environment, the actual rate of aging can vary greatly from pet to pet.
For dogs, it is based on the method provided by the American Veterinary Medical Association (AVMA). The first year of life is about 15 human years, and the second year adds about 9 more, making a 2-year-old dog about 24 in human years. After that, it splits by size. Based on the size-based conversion chart in the veterinary textbook Dog Owner's Home Veterinary Handbook, small dogs age about 4 human years per year, medium dogs about 5, and large dogs about 5–6.
For cats, it uses the "15-9-4" method from life stage standards such as those of the American Animal Hospital Association (AAHA): 15 years for the first year, 9 more for the second, and 4 more for each year after that. The basis and care points for each stage are summarized in the age conversion guide.
| Dog age | Small | Medium | Large |
|---|---|---|---|
| 6 months | 10 years | 10 years | 10 years |
| 1 year | 15 years | 15 years | 15 years |
| 2 years | 24 years | 24 years | 24 years |
| 3 years | 28 years | 28 years | 28 years |
| 5 years | 36 years | 37 years | 40 years |
| 7 years | 44 years | 47 years | 50 years |
| 10 years | 56 years | 60 years | 66 years |
| 12 years | 64 years | 69 years | 77 years |
| 15 years | 76 years | 83 years | 93 years |
Even at the same age, human age diverges by size. At 10 years old, a small dog is middle-aged, but a large dog is already a senior.
| Cat age | Human age | Cat age | Human age |
|---|---|---|---|
| 6 months | 10 years | 7 years | 44 years |
| 1 year | 15 years | 10 years | 56 years |
| 2 years | 24 years | 12 years | 64 years |
| 3 years | 28 years | 15 years | 76 years |
| 5 years | 36 years | 20 years | 96 years |
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Q. Do you multiply a dog's age by 7 to get its human age?
No. Dogs and cats age non-linearly: they mature much faster when young and then slow down. The first year of life equals about 15 human years, which the age × 7 method greatly underestimates. Veterinary practice instead counts 15 years for the first year and 9 more for the second, then adds rates by size for dogs and 4 years per year for cats.
Q. How old is a 1-year-old dog in human years?
About 15 years old. A 2-year-old dog is about 24, and after that it depends on size. At 10 years old, a small dog is about 56 in human years, a medium dog about 60, and a large dog about 66 — larger dogs age faster.
Q. How old is a 1-year-old cat in human years?
About 15 years old. A 2-year-old cat is about 24, and after that you add 4 human years for each additional year. So a 5-year-old cat is about 36, a 10-year-old about 56, and a 15-year-old about 76.
Q. Why do larger dogs age faster than smaller dogs?
Large dogs grow faster and their cells age faster too, so their average lifespan is shorter. At the same age of 10, a small dog is about 56 in human years (middle age) while a large dog is about 66 (senior), so their life stages differ. That is why the timing of health checkups and senior care should also differ by size.
Q. What if I don't know my pet's exact age?
If you adopted or rescued your pet and don't know its age, a veterinarian can estimate it from the condition of the teeth, eyes (lens), muscle mass, and more. Entering that estimated age into this calculator can help you gauge the life stage and the level of care needed.