How to use it
Choose the animal. For a dog, pick its size, or crossbreed if it is a mix. Put in their age in years, and months if you know them. The answer appears as you type. Nothing you put in is stored or sent.
How we work it out
This is our own method, not "times seven" and not anyone else's formula. We ask one question: how far through a typical life is this animal? Then we take the same share of a typical human life.
Say a medium-sized dog is 6 years and 3 months old. The typical figure for medium breeds is 12.5 years, so the dog is halfway through. Halfway through a human life of 81.05 years is about 41, so the answer is 41.
The animal figures come from UK studies; our page on how long pets live lists them all with links. The human figure is the middle of the latest UK life expectancy at birth from the Office for National Statistics: 83.0 years for women and 79.1 for men in 2022 to 2024. The line under the calculator shows the figure in use and when it was last checked.
What it can and can't tell you
It is a way to picture their age, not a health check. A straight line is simple, and that is the point, but real animals don't age in a straight line. Puppies and kittens grow up far faster than children do, so a one-year-old reads young here.
The small-pet figures are lower than many owners expect. For rabbits, guinea pigs and hamsters, the studies give the median age of those that died, from vet records, so a healthy older rabbit can come out "older" than a person ever gets. When a pet is past the typical figure, the calculator says so.