Pet Age in Human Years Calculator

About this calculator

The old “multiply by 7” rule for dog years is a myth — aging doesn’t track linearly with human years, since a dog reaches sexual maturity and much of its adult development within its first year or two. The modern epigenetic clock formula, developed from DNA methylation studies at UC San Diego, gives dog age in human-equivalent years as human age = 16 × ln(dog age) + 31, which captures the rapid early aging and the subsequent slowdown far better than a flat multiplier. Cats follow a different, more traditional formula: roughly 15 human years for the first year of life, 9 more for the second (24 total by age two), then about 4 additional human years for every year after that.

Pet owners and veterinarians use age-in-human-years less as a literal biological claim and more as an intuitive way to gauge a pet’s life stage — knowing that a 10-year-old dog is roughly “68” by the epigenetic formula frames expectations around senior health screening, joint care and diet changes in terms most owners already understand from human aging.

This calculator takes your pet’s species (dog or cat) and actual age, and returns the human-year equivalent using the current epigenetic and feline formulas.