Dog years explained
How to convert dog years to human years
By Toheed MehmoodReviewed How we check facts
In short
A dog's first year equals about 15 human years and the second about 9 more, so a 2-year-old dog is roughly 24. After that each year adds 4 to 7 human years depending on size: a 7-year-old small dog is about 44, while a 7-year-old giant breed is about 56.
- 1-year-old dog
- ≈ 15 human years
- 2-year-old dog
- ≈ 24 human years
- Senior, small breeds (AVMA)
- 8–11 years
- Senior, giant breeds (AVMA)
- 6–7 years
Dog years to human years chart
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 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 |
Small: under 20 lb (9 kg). Medium: 20–50 lb. Large: 50–90 lb. Giant: over 90 lb (41 kg). Use the weight your dog will reach as an adult, not their weight as a puppy.
Is one dog year really seven human years?
No. The American Veterinary Medical Association says dogs do not age at a rate of seven human years per year. Dogs grow up much faster than people at the start (a one-year-old dog can already have puppies) and then age more slowly, at a pace that depends on size.
Why do big dogs age faster?
Large and giant breeds have shorter lifespans than small breeds, so their later years are compressed. The AVMA considers small dogs senior at about 8 to 11, medium dogs at 8 to 10, large dogs at 8 to 9 and giant breeds at 6 to 7.
The DNA-based dog age formula
A 2020 study from the University of California San Diego compared age-related chemical changes to DNA in Labrador Retrievers and people. It suggests human age ≈ 16 × ln(dog age) + 31, which makes young dogs “older” than the chart: a 1-year-old Labrador matches a 31-year-old human, and a 7-year-old is about 62.
The size chart is the one vets most often use day to day. The DNA formula is shown as a second view; it was built from one breed, so treat it as interesting rather than exact.
Dog life stages
- Puppy
- Birth until about 1 year (up to 18 months for large and giant breeds).
- Young adult
- Until around 3 years old.
- Mature adult
- From about 3 years until the senior years for their size.
- Senior
- Roughly the last quarter of expected lifespan; see the size ranges above.
Life stages follow the American Animal Hospital Association's canine guidelines. Ask your vet how they apply to your dog, especially if their breed has known health risks. Have a cat too? Try the Cat Age Calculator.
Common questions
How old is a 5-year-old dog in human years?
About 36 for small, medium and large dogs, and about 45 for giant breeds.
How old is a 10-year-old dog in human years?
About 56 for a small dog, 60 for a medium dog, 66 for a large dog and 79 for a giant breed.
How do I know my dog's size category?
Use your dog's expected adult weight: small under 20 lb (9 kg), medium 20–50 lb, large 50–90 lb, giant over 90 lb.
My rescue dog's birthday is unknown. What do I enter?
Enter the age your vet estimated in years and months. Vets judge age from teeth, eyes and coat, so use their best guess.
Sources
- Senior pets · American Veterinary Medical Association (AVMA)
- Canine life stage definitions (2019 Canine Life Stage Guidelines) · American Animal Hospital Association (AAHA)
- Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome · Wang et al., Cell Systems (2020), via PubMed Central