How old is my dog in human years? A 1-year-old dog is about 15 in human years, a 2-year-old is about 24, a 5-year-old medium dog is about 39, a 10-year-old medium dog is about 64, and a 15-year-old medium dog is about 89. A small dog ages more slowly after age 2, adding about 4 human years per year, while a giant dog ages fastest, adding about 7 per year — so a 10-year-old toy dog is about 56, and a 10-year-old giant dog is about 80. This guide answers the question properly: the model vets use, the full chart, worked examples at every age, and what the number means for food, exercise, and vet visits. Every figure is an estimate, not an exact conversion, and the stage of life matters more than the number. The dog age calculator works out the figure for your dog's exact age and size.
The short version is: a 1-year-old dog is about 15 in human years, a 2-year-old is about 24, and after that a dog adds about 4 to 7 human years per year, depending on its size. The old rule of 'multiply by seven' is simple but wrong — it gives 35 for a 5-year-old dog, against about 39 on the size model, and it is wrong in the other direction for puppies and kittens. The dog age calculator guide gives the full model, and the how to calculate dog age guide gives the step-by-step method.
How old is my dog in human years? The model
The model most veterinarians use is the AVMA/AKC size model: the first year of a dog’s life equals about 15 human years, the second year brings the total to about 24 human years, and after that you add about 4 human years per dog year for a toy or small dog, about 5 for a medium dog, about 6 for a large dog, and about 7 for a giant dog. The formula for a dog aged two years or more is therefore: human years is approximately 24 plus the dog’s age minus 2, multiplied by the rate for its size.
A second way to estimate a dog’s human age comes from a 2020 epigenetic study by Wang and colleagues at the University of California, San Diego, published in Cell Systems: human age equals 16 times the natural logarithm of the dog’s age, plus 31. For a 5-year-old dog that gives about 57 human years, and for a 10-year-old about 68. The two models agree best in middle age and differ most in very young and very old dogs. Use the stage, not the number, to make decisions about food, exercise, and vet visits.
Worked examples: how old is my dog?
A 1-year-old dog is about 15 in human years, a 2-year-old is about 24, a 5-year-old medium dog is about 39, a 10-year-old medium dog is about 64, and a 15-year-old medium dog is about 89. A small dog ages more slowly after age 2, adding about 4 human years per year, while a giant dog ages fastest, adding about 7 per year — so a 10-year-old toy dog is about 56, and a 10-year-old giant dog is about 80.
To work it out for your own dog, find its age in the table below, or use the dog age calculator. If your dog is between two ages in the table, take the nearer one — the models are estimates, and a year either way does not change the stage of life. The dog age chart by breed guide gives the figures breed by breed, and the dog age chart by size guide gives them by size.
| Dog age | Toy | Small | Medium | Large | Giant |
|---|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 | 15 |
| 2 years | 24 | 24 | 24 | 24 | 24 |
| 3 years | 28 | 28 | 29 | 30 | 31 |
| 5 years | 36 | 36 | 39 | 42 | 45 |
| 7 years | 44 | 44 | 49 | 54 | 59 |
| 10 years | 56 | 56 | 64 | 72 | 80 |
| 12 years | 64 | 64 | 74 | 84 | 94 |
| 15 years | 76 | 76 | 89 | 102 | 115 |
What the number means for care
A dog that is a puppy or kitten needs puppy or kitten food, fed little and often, and gentle exercise while its joints are still developing. An adult dog needs measured food and daily exercise, and a vet check once a year. A senior dog needs twice-yearly vet checks, a diet review, and exercise that stays regular but gentler. The number in the chart is a guide to the stage, not a prescription — and a dog's weight, health, and activity matter as much as its age.
Once a dog passes its senior boundary — about 10 years for a toy or small dog, 8 to 10 for a medium dog, 7 to 8 for a large dog, and 6 to 7 for a giant dog — expect gradual change rather than a sudden switch: sleep increases, play sessions get shorter, and the dog may become more set in its routines. Hearing and sight can dull, so an older dog may startle more easily or hesitate in the dark. The senior dog diet guide covers feeding in the senior years, and the when is a dog considered a senior guide gives the thresholds by size.
How old is my dog compared with other dogs?
A 5-year-old dog is a young adult, a 10-year-old dog is a senior or near-senior depending on its size, and a 15-year-old dog is very old — older than most dogs ever get. A toy dog at 15 is about 76 in human years, and a giant dog at 15 would be about 115, which is beyond the typical lifespan of 7 to 10 years for a giant breed. Those comparisons show why the number matters: it tells you where your dog is in its life, and what to expect next.
But two dogs of the same age can be in very different shape — one may be lean, fit, and bright-eyed at 10, while another may be stiff and slowing down at 8 — because weight is one of the biggest factors owners can influence. A dog kept at a healthy weight tends to age more slowly in practical terms than one carrying extra weight, because excess weight strains joints and organs. The dog ideal weight calculator works out a target weight range, and the how long do dogs live guide gives the lifespans by size.
Common mistakes
The most common mistake is the 'multiply by seven' rule, which gives 35 human years for a 5-year-old dog, against about 39 on the size model. The second is using the dog model for a cat, or the cat rule for a dog. The third is taking the number too literally: the models give an estimate of the stage of life, not an exact conversion. The fourth is forgetting size for dogs: a large dog ages faster than a small one, so a 10-year-old Great Dane is much older in human years than a 10-year-old Chihuahua.
The fifth mistake is using age alone to decide food or care: a dog's weight, health, and activity matter as much as its age, and a vet check is worth more than a chart. The how to calculate dog age guide gives the step-by-step method, and the dog lifespan calculator puts age in the context of lifespan.
For related reading, see the dog age calculator, the dog age calculator guide, the how to calculate dog age guide, the dog age chart by size guide, the when is a dog considered a senior guide, the dog lifespan estimator.
Frequently asked questions
How old is my dog in human years?
A 1-year-old dog is about 15 in human years, a 2-year-old is about 24, and after that a dog adds about 4 to 7 human years per year, depending on its size. A 5-year-old dog is about 39, and a 10-year-old is about 64. Use the table above, or the dog age calculator, for your dog's exact age and size.
How old is a 5-year-old dog in human years?
A 5-year-old medium dog is about 37 in human years — a toy or small dog is about 36, a large dog about 42, and a giant dog about 45. The 'multiply by seven' rule gives 35, which is close for a 5-year-old by chance, but it is wrong at every other age.
How old is a 10-year-old dog in human years?
A 10-year-old toy or small dog is about 56 in human years, a medium dog about 64, a large dog about 72, and a giant dog about 80. A 10-year-old dog is a senior or near-senior, depending on its size, and it should have twice-yearly vet checks from its senior boundary.
Is the 'multiply by 7' rule right?
No. Multiplying by seven gives 35 human years for a 5-year-old dog, against about 39 on the size model — and it is wrong in the other direction for puppies and kittens, where a 1-year-old dog is already about 15 in human years, not 7.
When is my dog a senior?
A dog is usually considered a senior from about 10 years for a toy or small dog, 8 to 10 for a medium dog, 7 to 8 for a large dog, and 6 to 7 for a giant dog. Those are rough guides, and your vet may move the boundary earlier or later depending on your individual dog's health.
How long will my dog live?
Typical lifespans by size are about 12 to 16 years for toy breeds, 12 to 15 for small breeds, 10 to 14 for medium breeds, 10 to 12 for large breeds, and 7 to 10 for giant breeds. Those are ranges, not promises. The dog lifespan calculator puts your dog's age in the context of its expected lifespan.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.