The old ×7 rule is wrong: dogs mature very fast early on and slow down later. Researchers at UC San Diego mapped dog DNA aging to human aging and found a logarithmic curve. This calculator uses that science, adjusted by size.
For dogs over 1 year we use the epigenetic clock formula published by Ideker et al. (Cell Systems, 2020): human age = 16 × ln(dog age) + 31, derived from DNA methylation in Labrador Retrievers, then adjusted by size — small breeds age slower in later years, giant breeds faster. Under 1 year we interpolate development milestones. It's an estimate for healthy dogs, not a veterinary assessment.