Free tool
Pet age calculator: dog and cat years to human years
Enter your pet's age and our pet age calculator shows it in human years. Dogs are worked out by size, because small and giant dogs count their years differently; cats follow the usual cat chart.
Is one dog year really seven human years?
The seven-year rule is easy to remember but doesn't match how dogs grow up. Most dogs are roughly 15 in human terms at their first birthday and about 24 at their second. After that, each year counts for around 4 human years in a small dog and up to 7 or more in a giant breed.
Cats follow a similar curve with no size groups: about 15 at one, 24 at two, then roughly 4 human years for every year after that.
Which size is my dog?
Go by their grown-up size: small up to about 9 kg (20 lb), medium 9 to 23 kg, large 23 to 45 kg and giant above that. For a mixed breed, pick the size that's closest. For a puppy, pick the size they'll grow into.
Questions
How old is a 5-year-old dog in human years?
About 36 for a small or medium dog, 36 for a large dog and 45 for a giant breed. The differences grow after the fifth birthday: at 10, a small dog is about 56 and a giant dog about 79.
How old is a 10-year-old cat in human years?
About 56. Cats reach roughly 15 at their first birthday and 24 at their second, then add about 4 human years each year.
How exact is this?
It's a rule of thumb, not a measurement: two dogs of the same age and size won't be identical. The charts give a fair human-years comparison and a fun number to share.
My pet's birthday is a mystery. What should I enter?
Your best guess is fine. If you know roughly when they came home and how old they were then, add the two together. Then find their sign from the day they came home with the sign calculator.