Dog Age to Human
Dog age in human-equivalent years (UCSD formula).
Formula
Human age = 16 ln(dog age) + 31
How to use
- 1Enter your dog’s actual age in years (use decimals for months, e.g. 1.5).
- 2Read the human-equivalent age instantly.
- 3Use it as a prompt to think about life stage and preventive care.
About this calculator
The old rule that one dog year equals seven human years is a myth. Dogs race through puppyhood, then slow down. This calculator uses a formula grounded in a 2019 UC San Diego study of DNA methylation, so the result tracks how a dog’s body actually ages rather than a rough guess.
Formula explained
Human age = 16 × ln(dog age) + 31. The natural logarithm produces the fast-then-slow curve, 16 scales it to human years and 31 anchors the youngest ages. It is defined for dogs older than about 0.1 years and fits medium to large breeds best.
Worked example
16 × ln(5) + 31 = 16 × 1.609 + 31 ≈ 57 human years. A 2-year-old dog is about 42, so the jump from year 2 to year 5 adds only ~15 - aging is front-loaded.
Tips & notes
- Start yearly senior health check-ups once a dog reaches about seven years.
- Twice-yearly vet visits make sense for older or larger dogs.
- Watch weight, mobility and appetite, since changes there often appear first.