How old is my dog in human years? It is the question every dog owner asks, and the answer is not 'multiply by seven' — that rule is simple but wrong. 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. This guide is the dog age calculator in words: the model, the full chart, the life stages, and the senior age, with worked examples. 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. A 5-year-old dog is about 39 in human years, and a 10-year-old is about 64. Use the table below for your dog's age and size, or the dog age calculator for the exact figure. The how old is my dog in human years guide gives the same model with worked examples for every age.
How to calculate a dog's age in human years
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.
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. The researchers compared chemical marks on the DNA of dogs and humans as they age and produced this formula: 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. Neither model is a veterinary standard for treating your dog, and the UCSD formula is a research model, not a clinical tool — but if both models put your dog in the same broad stage of life, you can be confident about the stage, even though the exact number differs.
Use the stage, not the number, to make decisions about food, exercise, and vet visits: a dog that is a puppy or kitten needs puppy or kitten food and gentle exercise, an adult needs measured food and daily exercise, and a senior needs twice-yearly vet checks and gentler exercise. The number in the chart is a guide to the stage, not a prescription. The dog age in human years chart and the cat age in human years chart put every age on one page.
Dog age chart: human years by age and size
The table below gives the human-age equivalents for dogs aged 1 to 15, by size, using the AVMA/AKC size model.
| 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 |
Read the table from top to bottom and the pattern is clear: a dog ages fast in its first two years — 15 human years in the first year, and 24 by the end of the second — and then slows down. A large dog then ages faster than a small one, adding about 6 or 7 human years per year against about 4 for a toy or small dog, which is why the gap between sizes grows with age. The dog years to human years converter and the cat years to human years converter give the same figures as a converter.
Life stages for dogs
Dogs move through three broad life stages, and the boundaries depend on size, not on the breed name:
Puppy or kitten (birth to about 12–18 months). Growth is rapid, especially in the first year. A puppy or kitten reaches about half its adult weight well before its first birthday, but bones and joints keep maturing after that. Feed a puppy or kitten food, feed little and often, and keep exercise gentle while joints are still developing.
Adult (about 18 months to senior age). Growth is finished and weight should be stable. This is the longest stage and the easiest to manage: consistent food, daily exercise suited to the breed, and a vet check once a year.
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). The last quarter or so of a typical lifespan. Energy often drops, joints stiffen, and senses dull. Vet checks should move to twice a year, food may need adjusting, and exercise should stay regular but gentler.
Those boundaries are approximate. A dog that is lean, active, and healthy may act like an adult well past its size's senior boundary, while one with a health problem may need senior care earlier. The when is a dog considered a senior guide gives the thresholds by size, and the senior dog diet guide covers feeding in the senior years.
When is a 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. That is a rough guide, not a birthday: a dog that is lean, active, and healthy may act like an adult well past its senior boundary, while one with a health problem may need senior care earlier. Your vet may move the boundary earlier or later depending on your individual dog's health.
Once a dog passes its senior boundary, 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. Appetite can change in either direction, so weigh food rather than guessing, and weigh the dog monthly so slow weight gain or loss does not creep up unnoticed. The senior dog lifespan guide explains what the senior years mean for the whole of a dog's remaining life.
Common mistakes with dog age
The most common mistake is the 'multiply by seven' rule: 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. The second mistake is using the dog model for a cat, or the cat rule for a dog: dogs and cats age differently, and the models are not interchangeable. The third is taking the number too literally: the models give an estimate of the stage of life, not an exact conversion, and two dogs of the same age can be in very different shape.
The fourth mistake is forgetting size: 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 — about 80 against about 56. The fifth 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 how old is my dog in human years guide, the dog age chart by size guide, the when is a dog considered a senior guide, the dog lifespan estimator, the how to calculate dog age guide.
Frequently asked questions
How old is my dog in human years?
Use the AVMA/AKC size model for dogs: 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.
Is the 'multiply by 7' rule right for a dog?
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. Use the AVMA/AKC size model in the table above instead.
How old is a 10-year-old dog in human years?
It depends on size for dogs and not for cats: 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 cat of any size is about 56. Use the table above for your dog's size.
When is a dog considered 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 do dogs 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.
How can I help my dog live longer?
Keep it at a healthy weight with measured food, exercise it every day, keep its teeth clean, keep vaccinations and parasite control up to date, and take it to the vet once a year as an adult and twice a year as a senior. The dog food guide is the starting point for weight control — or use the dog food calculator for your dog's exact weight.
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.