Forget what you may have heard about 1 cat year equaling 7 years – it’s a myth. Kittens mature very quickly, and are the equivalent of a human teenager by the time they are several months old. Cats reach human “adulthood” when they are about 1½ years old. After they reach 2 years old, cats age the equivalent of 4 human years for every year that goes by. (That’s one reason why annual check-ups are important. Cats do a lot of aging in that one year!)
Every cat is an individual and ages at a slightly different rate, so converting your cat’s age into human age is not an exact science. But the chart below will give a good estimate of how old your cat is in human years.