Dog Age Calculator: Dog Years to Human Years
Find out how old your dog is in human years, based on their age and size or breed
Last updated: 8 October 2026
A 1-year-old dog is about 15 in human years and a 2-year-old about 24. After that, each dog year adds roughly 4 human years for small dogs, 4–5 for medium, 5–6 for large and about 7 for giant breeds.
So a 10-year-old dog is about 56 in human years if small, 60 if medium, 66 if large and 79 if giant. Use the calculator for your dog’s exact age, see the dog years to human years chart, or convert human years to dog years.
Calculate Your Dog's Human Age
Why the 7-Year Rule is Wrong
The popular "multiply by 7" rule is a myth that oversimplifies how dogs age. In reality, dogs mature much faster in their early years - a 1-year-old dog is more like a 15-year-old human, not a 7-year-old.
Size matters too. A Great Dane at age 7 is approaching old age, while a Chihuahua of the same age is still in its prime. Our calculator uses the widely used size-based chart shown below, so the result always matches the chart.
Dog Years to Human Years Chart
Human-age equivalent for each year of a dog’s life, by size. If you have chosen a breed or size above, its column is highlighted.
| Dog’s age | Small (under 9kg) | Medium (9-22kg) | Large (22-40kg) | Giant (over 40kg) |
|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 12 |
| 2 years | 24 | 24 | 24 | 22 |
| 3 years | 28 | 28 | 28 | 31 |
| 4 years | 32 | 32 | 32 | 38 |
| 5 years | 36 | 36 | 36 | 45 |
| 6 years | 40 | 42 | 45 | 49 |
| 7 years | 44 | 47 | 50 | 56 |
| 8 years | 48 | 51 | 55 | 64 |
| 9 years | 52 | 56 | 61 | 71 |
| 10 years | 56 | 60 | 66 | 79 |
| 11 years | 60 | 65 | 72 | 86 |
| 12 years | 64 | 69 | 77 | 93 |
| 13 years | 68 | 74 | 82 | 100 |
| 14 years | 72 | 78 | 88 | 107 |
| 15 years | 76 | 83 | 93 | 114 |
| 16 years | 80 | 87 | 99 | 121 |
Figures follow the widely used size-based chart published by Purina UK. They are estimates: individual dogs age differently depending on breed, genetics and health.
Human Years to Dog Years
Want to know what a person’s age would be in dog years? Enter a human age and choose a dog size.
How Dogs Age by Size
Dogs don't age uniformly - their size plays a crucial role in how quickly they mature and how long they live. Understanding this can help you provide better care at each life stage.
Small Breeds (under 9kg)
Small dogs like Chihuahuas and Yorkshire Terriers age the slowest. They reach maturity quickly but then age gradually, often living 14-18 years. They become seniors around age 10-12.
Medium Breeds (9-22kg)
Breeds like Beagles and Border Collies typically live 10-14 years. They enter their senior years around 8-10 years old and benefit from preventive health care starting in middle age.
Large Breeds (22-40kg)
Labrador Retrievers and German Shepherds typically live 9-12 years. They age faster than smaller dogs and should be considered seniors by age 7-9. Joint care becomes important earlier.
Giant Breeds (over 40kg)
Great Danes and Mastiffs have the shortest lifespans at 7-10 years. They age rapidly and can be considered seniors as early as 5-6 years old. Early health monitoring is essential.
Why Do Large Dogs Age Faster?
Scientists believe several factors contribute to this phenomenon. Larger dogs grow faster during puppyhood, which may cause more cellular damage. Their bodies work harder to maintain their size, putting more strain on organs. Additionally, the rapid growth may lead to earlier onset of age-related diseases.
Life Stage Care Guide
- Puppy (0-1 year):
- Focus on proper nutrition, vaccination schedules, socialisation, and basic training.
- Young Adult (1-2 years):
- Establish exercise routines, complete training, maintain healthy weight.
- Adult (2 years to middle age):
- Regular vet checkups, dental care, consistent exercise, balanced diet.
- Mature/Senior (see sizes above):
- More frequent health screenings, joint supplements, adjusted exercise, comfortable environment.
Frequently Asked Questions
How do you calculate a dog's age in human years?
The widely used size-based chart counts a dog's first year as about 15 human years and the second as about 9 more (24 in total). After that it adds roughly 4 human years per year for small dogs, 4-5 for medium, 5-6 for large and about 7 for giant breeds. Giant breeds start a little lower (about 12 at one year) but age fastest. See the full chart.
Is the 7-year rule accurate for dogs?
No, the "multiply by 7" rule is an outdated myth. Dogs age much faster in their first two years - a 1-year-old dog is already a teenager in human terms, and a 2-year-old is a young adult. The rate of aging also varies significantly based on breed size.
Why do large dogs age faster than small dogs?
Research suggests that large dogs age faster due to their accelerated growth rate during puppyhood, which may lead to earlier cellular aging. Their bodies also work harder to maintain their larger size, putting more strain on organs and joints over time.
What age is a dog considered senior?
This varies significantly by size. Small dogs (under 9kg) are considered seniors around 10-12 years. Medium dogs become seniors at 8-10 years. Large dogs enter their senior years at 7-9 years. Giant breeds may be considered seniors as early as 5-6 years.
How old is a 10 year old dog in human years?
A 10-year-old dog's human equivalent age depends on their size: Small breeds are approximately 56 human years. Medium breeds are about 60 human years. Large breeds are roughly 66 human years. Giant breeds are approximately 79 human years.
How old is a 1 year old dog in human years?
A 1-year-old dog is about 15 in human years for small, medium and large breeds, and about 12 for giant breeds. By 2 years old most dogs are about 24 in human years (22 for giant breeds).
How old is a 14 year old dog in human years?
A 14-year-old dog is about 72 in human years for small breeds, 78 for medium breeds, 88 for large breeds and 107 for giant breeds.
What is 18 years in dog years?
An 18-year-old person is roughly the same age as a dog of about 1 year 4 months (or about 1 year 7 months for giant breeds). Going the other way, a small dog that is 18 years old is about 88 in human years. Use the human years to dog years converter for any age.
How can I help my dog live longer?
Key factors for longevity include maintaining a healthy weight, providing regular exercise appropriate for their age and size, feeding a balanced diet, keeping up with preventive veterinary care, dental hygiene, mental stimulation, and lots of love and attention.