Cat age by year
Or see the full cat years to human years chart.
How old is your pet in human years?
Pick cat or dog, enter their age, and see the human equivalent and life stage. You can also work backwards from a human age.
Dog size
Dog age by year
Dogs age at different rates by size, so there is also a chart for each:
Or see the full dog years to human years chart.
How the calculations work
Cats
A cat's first year equals about 15 human years, the second adds 9 more, and every year after that adds 4. Months count proportionally, so a 6-month-old kitten comes out at about 8.
Dogs
Dogs start the same way, with 15 human years for the first year and 9 more for the second. After that, the rate depends on size: bigger dogs age faster. The calculator follows a commonly used size-based chart and blends between whole years for ages in between.
Both are averages. Breed, diet, health, and lifestyle all affect how a pet ages. Read more about the method.
Common questions
How old is a 1-year-old cat or dog in human years?
About 15 for both. The first year counts as roughly 15 human years, and the second adds about 9 more, so a 2-year-old is around 24.
Do small dogs live longer than big dogs?
Generally, yes. Larger dogs tend to age faster and have shorter lives, which is why the chart gives bigger dogs a higher human age at the same calendar age.
When is a cat or dog considered a senior?
Vets commonly treat cats as seniors from about 11. For dogs it depends on size: from about 10 for small dogs, 7 for medium, and 5 to 7 for large and giant dogs.