Human years to dog years
The reverse of the usual question: which dog age matches a human age? Enter an age below or read the table. The conversion inverts the size-adjusted chart, so it runs faster for big dogs after age two.
Human years to dog years table
| Human age | Small dog | Medium dog | Large dog | Giant dog |
|---|---|---|---|---|
| 1 | 1 mo | 1 mo | 1 mo | 1 mo |
| 2 | 2 mo | 2 mo | 2 mo | 2 mo |
| 3 | 2 mo | 2 mo | 2 mo | 2 mo |
| 4 | 3 mo | 3 mo | 3 mo | 3 mo |
| 5 | 4 mo | 4 mo | 4 mo | 4 mo |
| 6 | 5 mo | 5 mo | 5 mo | 5 mo |
| 7 | 6 mo | 6 mo | 6 mo | 6 mo |
| 8 | 6 mo | 6 mo | 6 mo | 6 mo |
| 9 | 7 mo | 7 mo | 7 mo | 7 mo |
| 10 | 8 mo | 8 mo | 8 mo | 8 mo |
| 11 | 9 mo | 9 mo | 9 mo | 9 mo |
| 12 | 10 mo | 10 mo | 10 mo | 10 mo |
| 13 | 10 mo | 10 mo | 10 mo | 10 mo |
| 14 | 11 mo | 11 mo | 11 mo | 11 mo |
| 15 | 1 yr | 1 yr | 1 yr | 1 yr |
| 16 | 1.1 yr | 1.1 yr | 1.1 yr | 1.1 yr |
| 17 | 1.2 yr | 1.2 yr | 1.2 yr | 1.2 yr |
| 18 | 1.3 yr | 1.3 yr | 1.3 yr | 1.3 yr |
| 19 | 1.4 yr | 1.4 yr | 1.4 yr | 1.4 yr |
| 20 | 1.6 yr | 1.6 yr | 1.6 yr | 1.6 yr |
| 21 | 1.7 yr | 1.7 yr | 1.7 yr | 1.7 yr |
| 22 | 1.8 yr | 1.8 yr | 1.8 yr | 1.8 yr |
| 23 | 1.9 yr | 1.9 yr | 1.9 yr | 1.9 yr |
| 24 | 2 yr | 2 yr | 2 yr | 2 yr |
| 25 | 2.3 yr | 2.2 yr | 2.2 yr | 2.1 yr |
| 26 | 2.5 yr | 2.4 yr | 2.3 yr | 2.3 yr |
| 27 | 2.8 yr | 2.6 yr | 2.5 yr | 2.4 yr |
| 28 | 3 yr | 2.8 yr | 2.7 yr | 2.6 yr |
| 29 | 3.3 yr | 3 yr | 2.8 yr | 2.7 yr |
| 30 | 3.5 yr | 3.2 yr | 3 yr | 2.9 yr |
| 35 | 4.8 yr | 4.2 yr | 3.8 yr | 3.6 yr |
| 40 | 6 yr | 5.2 yr | 4.7 yr | 4.3 yr |
| 45 | 7.3 yr | 6.2 yr | 5.5 yr | 5 yr |
| 50 | 8.5 yr | 7.2 yr | 6.3 yr | 5.7 yr |
| 55 | 9.8 yr | 8.2 yr | 7.2 yr | 6.4 yr |
| 60 | 11 yr | 9.2 yr | 8 yr | 7.1 yr |
| 65 | 12.3 yr | 10.2 yr | 8.8 yr | 7.9 yr |
| 70 | 13.5 yr | 11.2 yr | 9.7 yr | 8.6 yr |
| 75 | 14.8 yr | 12.2 yr | 10.5 yr | 9.3 yr |
| 80 | 16 yr | 13.2 yr | 11.3 yr | 10 yr |
| 85 | 17.3 yr | 14.2 yr | 12.2 yr | 10.7 yr |
| 90 | 18.5 yr | 15.2 yr | 13 yr | 11.4 yr |
| 95 | 19.8 yr | 16.2 yr | 13.8 yr | 12.1 yr |
| 100 | 21 yr | 17.2 yr | 14.7 yr | 12.9 yr |
Inverse of the size-adjusted chart: human ages up to 15 map onto a dog's first year, 15 to 24 onto its second, then 4 (small), 5 (medium), 6 (large) or 7 (giant) human years per dog year. The other direction, with life stages: dog age chart and dog years by age.
Frequently asked questions
How many dog years is one human year?
It depends where in life you are. In a dog's first year, one human year is worth about 1/15 of a dog year (roughly 24 days); after age two, one human year is about a quarter of a dog year for small dogs and a seventh for giant breeds. The old 7:1 rule only roughly fits large dogs in middle age.
How old is 18 in dog years?
A human aged 18 matches a dog of about 1 year and 4 months, whatever the size: dogs reach the equivalent of late adolescence during their second year.
How old would I be as a dog?
Find your age in the table and read across for a dog of your preferred size. A 40-year-old human is a 6-year-old small dog, a 5-year-old medium dog or a 4-year-old giant breed.
Why is the conversion different for small and large dogs?
Large dogs age faster after maturity: in UK data large breeds had a median lifespan of 11.9 years against 12.7 for small breeds, and giants live 7 to 10 years. The chart adds 4 human years per dog year for small dogs and 7 for giants, so the reverse conversion runs faster for big dogs.
Sources
- American Veterinary Medical Association. Senior pets: how old is old? www.avma.org/resources-tools/pet-owners/petcare/senior-pets
- 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