Dog Age Calculator
How old is my dog in human years?
A 3-year-old dog is about 28 in human years: the first year counts as about 15, the second adds about 9, and each year after adds 4 to 7 depending on size.
In human years
-
- Life stage
- -
- Other sizes
- -
- 2020 DNA study formula (Labrador)
- -
For reference only. Breed, size and health all make a difference.
Dog age chart by size
AKC chart. Small up to 20 lb, medium 21–50 lb, large 51–100 lb, giant over 100 lb.
| Dog age | Small | Medium | Large | Giant |
|---|---|---|---|---|
| 1 | 15 | 15 | 15 | 12 |
| 2 | 24 | 24 | 24 | 22 |
| 3 | 28 | 28 | 28 | 31 |
| 4 | 32 | 32 | 32 | 38 |
| 5 | 36 | 36 | 36 | 45 |
| 6 | 40 | 42 | 45 | 49 |
| 7 | 44 | 47 | 50 | 56 |
| 8 | 48 | 51 | 55 | 64 |
| 9 | 52 | 56 | 61 | 71 |
| 10 | 56 | 60 | 66 | 79 |
| 11 | 60 | 65 | 72 | 86 |
| 12 | 64 | 69 | 77 | 93 |
| 13 | 68 | 74 | 82 | 100 |
| 14 | 72 | 78 | 88 | 107 |
| 15 | 76 | 83 | 93 | 114 |
| 16 | 80 | 87 | 99 | 121 |
Cat age chart
International Cat Care life stages
| Cat age | Human years | Life stage |
|---|---|---|
| 6 months | 10 | Kitten |
| 1 year | 15 | Junior |
| 2 years | 24 | Junior |
| 3 years | 28 | Prime |
| 4 years | 32 | Prime |
| 5 years | 36 | Prime |
| 6 years | 40 | Prime |
| 7 years | 44 | Mature |
| 8 years | 48 | Mature |
| 9 years | 52 | Mature |
| 10 years | 56 | Mature |
| 11 years | 60 | Senior |
| 12 years | 64 | Senior |
| 13 years | 68 | Senior |
| 14 years | 72 | Senior |
| 15 years | 76 | Geriatric |
| 16 years | 80 | Geriatric |
| 17 years | 84 | Geriatric |
| 18 years | 88 | Geriatric |
| 19 years | 92 | Geriatric |
| 20 years | 96 | Geriatric |
Something off with the result?
How it's calculated
AKC dog age chart · International Cat Care life stages
- Dogs: American Kennel Club (AKC) chart by size — 15 human years for the first year, 24 at age 2, then 4 to 7 years per year depending on size. This matches the AVMA guideline of 15 for year one, +9 for year two and about 4–5 per year after. Giant breeds start at 12 for the first year
- Cats: International Cat Care life-stage chart (with the AAHA and AAFP) — 10 at 6 months, 15 at 1 year, 24 at 2 years, then 4 per year
- Ages between rows (such as 5 years 6 months) are spread evenly between the two values. Past 16 for dogs and 25 for cats, the last yearly step is extended
- 2020 study formula: Wang et al., Cell Systems 11(2), 2020 — human age = 16 × ln(dog age) + 31 (Labrador Retrievers, age 1 and up)
- Not a health assessment. The birthday you enter never leaves this device
Frequently asked questions
How old is my dog in human years?
It depends on age and size. Using the American Kennel Club chart, a dog's first year is about 15 human years and the second adds about 9 more (24). After that, small dogs add about 4 years per year and giant breeds up to 7. A 5-year-old Beagle is about 36; a 5-year-old Great Dane is about 45.
Is one dog year really seven human years?
No. The 7-to-1 rule is an old rule of thumb with little science behind it. Dogs mature very fast in their first two years, then age more slowly, and bigger dogs age faster than smaller ones. That is why this calculator asks for your dog’s adult weight.
Why do big dogs age faster than small dogs?
Large and giant breeds have shorter life spans and reach their senior years sooner. From about age 6, a Labrador or a Mastiff counts as older in human terms than a Chihuahua of the same age. Pick the size by your dog’s full-grown weight, not its current puppy weight.
How do you calculate a cat’s age in human years?
A cat’s first year equals about 15 human years and its second brings it to 24. After that, each cat year adds about 4 human years, so a 10-year-old cat is about 56. This follows the life-stage chart from International Cat Care, developed with the AAHA and AAFP.
What is the DNA-based dog age formula?
In 2020, researchers at UC San Diego compared DNA methylation in Labrador Retrievers and people and proposed human age = 16 × ln(dog age) + 31. It was built from a single breed and only applies from age 1, so it is shown here for comparison only.