How old is my dog in human years?

Where the number comes from

Researchers at the University of California San Diego compared age-related changes in the DNA of Labrador Retrievers and people (Wang et al. 2020). Their formula:

• Human age ≈ 16 × ln(dog age) + 31.
• ln is the natural logarithm: the ln key on a calculator.
• Dogs grow up fast: by the formula a 1-year-old matches a person of about 31.
• Then ageing slows down: a 12-year-old matches a person of about 71.

Why not times seven?

Times seven turns a 1-year-old dog into a child of seven, but by the DNA clock it is already a young adult. The first year counts for a lot, later years for less.

Life stages

The American Animal Hospital Association's 2019 guidelines divide a dog's life into stages. The later ones depend on the expected lifespan of the breed:

• Puppy: Birth until rapid growth stops, at about 6 to 9 months.
• Young adult: Until body and behaviour have fully matured, in most dogs by 3 to 4 years.
• Mature adult: From then until the last quarter of the expected lifespan.
• Senior: The last quarter of the expected lifespan.

Dog years to human years

Good to know

• The formula was built on Labradors only. Breeds that live much longer or shorter may age at a different pace.
• The dogs in the study were up to 16 years old.
• Expected lifespans are breed medians from a UK study of 584,734 dogs (McMillan et al. 2024). Where the study had fewer than 30 deaths for a breed, we don't guess.
• Every dog is an individual. Your vet knows yours best.

Sources

• Wang T. et al.: Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome, Cell Systems 11 (2020), 176 to 185 ↗
• Creevy K. E. et al.: 2019 AAHA Canine Life Stage Guidelines, Journal of the American Animal Hospital Association 55 (2019), 267 to 290 ↗
• McMillan K. M. et al.: Longevity of companion dog breeds, those at risk from early death, Scientific Reports 14 (2024), 531 ↗