Dog age calculator
How old is your dog in human years? Enter age and size (or breed) for a size-adjusted answer, the epigenetic clock estimate, and your dog's current life stage.
- Life stage nowmature adult
- Senior from about8 years
- Typical lifespan for this size or breed10–14 years
- Roughly the human equivalent ofa 36-year-old
How the calculation works
Dogs mature quickly and then age at a pace that depends on body size. The calculator uses two methods:
- Size-adjusted chart. The first year counts as 15 human years, the second as 9 more (24 total), then every additional year adds 4 human years for toy and small dogs, 5 for medium, 6 for large and 7 for giant breeds. This is the approach used by the AVMA and AKC charts.
- Epigenetic clock. Wang and colleagues (2020) mapped DNA methylation changes in Labradors to humans and derived human age = 16 × ln(dog age) + 31. It puts a one-year-old dog at 31 human years and a four-year-old at 53, then slows: a ten-year-old is 68, a fourteen-year-old 73.
The two methods disagree in the middle years. Neither is a medical measurement, but both beat the old "multiply by seven" rule, which underestimates young dogs and overestimates seniors.
Dog years to human years chart
| Dog's age | Toy / small | Medium | Large | Giant | Epigenetic clock |
|---|---|---|---|---|---|
| 1 year | 15 | 15 | 15 | 15 | 31 |
| 2 years | 24 | 24 | 24 | 24 | 42 |
| 3 years | 28 | 29 | 30 | 31 | 49 |
| 4 years | 32 | 34 | 36 | 38 | 53 |
| 5 years | 36 | 39 | 42 | 45 | 57 |
| 6 years | 40 | 44 | 48 | 52 | 60 |
| 7 years | 44 | 49 | 54 | 59 | 62 |
| 8 years | 48 | 54 | 60 | 66 | 64 |
| 9 years | 52 | 59 | 66 | 73 | 66 |
| 10 years | 56 | 64 | 72 | 80 | 68 |
| 11 years | 60 | 69 | 78 | 87 | 69 |
| 12 years | 64 | 74 | 84 | 94 | 71 |
| 13 years | 68 | 79 | 90 | 101 | 72 |
| 14 years | 72 | 84 | 96 | 108 | 73 |
| 15 years | 76 | 89 | 102 | 115 | 74 |
| 16 years | 80 | 94 | 108 | 122 | 75 |
Frequently asked questions
Is one dog year really seven human years?
No. The 7:1 rule is a rough average that ignores how fast puppies mature. A one-year-old dog is closer to a 15-year-old human, a two-year-old to a 24-year-old, and after that each year adds about 4 to 7 human years depending on size, with big dogs aging fastest.
Why do large dogs age faster than small dogs?
Large and giant breeds reach old age sooner and have shorter lifespans. In the 2024 UK study of 584,734 dogs, small breeds had a median lifespan of 12.7 years, medium 12.5 and large 11.9. The size-adjusted chart reflects that by adding more human years per dog year for bigger dogs.
What is the epigenetic clock formula?
Wang et al. (2020) compared DNA methylation in Labradors and humans and found that human age ≈ 16 × ln(dog age) + 31. It says dogs age very fast in their first two years and then slow down, which matches sexual maturity at around one year. It was calibrated on one breed, so treat it as a second opinion.
When does my dog become a senior?
The AAHA life stage guidelines define senior as the last 25% of a breed's expected lifespan. For a Labrador with an expected 10 to 12 years, that is around 8. For a Chihuahua with 14 to 16 years, it is around 11. Pick a breed above and the calculator shows the exact threshold.
Sources
- Wang T, Ma J, Hogan AN, et al. Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome. Cell Systems. 2020;11(2):176-185. doi.org/10.1016/j.cels.2020.06.006
- Creevy KE, Grady J, Little SE, et al. 2019 AAHA Canine Life Stage Guidelines. Journal of the American Animal Hospital Association. 2019;55(6):267-290. www.aaha.org/resources/life-stage-canine-2019/
- McMillan KM, Bielby J, Williams CL, Upjohn MM, Casey RA, Christley RM. Longevity of companion dog breeds: those at risk from early death. Scientific Reports. 2024;14:531. doi.org/10.1038/s41598-023-50458-w
- American Veterinary Medical Association. Senior pets: how old is old? www.avma.org/resources-tools/pet-owners/petcare/senior-pets