Most people think that one year in a cat or dog’s life is equivalent to seven years in a human life. That is a myth. Felines actually mature much more quickly during the first two years of life than people do. And a cat’s rate of aging is not the same throughout its life compared to a human.
In a kitty’s first year, it reaches the human age of 15 — that difficult teenager stage of life. By the end of the cat’s second year of existence, it reaches the human equivalent of age 24 — a mid-twenties young adult (but without the responsibilities or college debt). After 2 years of age, each additional calender year is approximately equivalent to four ‘cat years’.
Feline Developmental Milestones
Kittens are weaned
Kittens start to lose their milk teeth
Most females cats have had a first heat
A cat reaches most of its height but will increase its body bulk
As a cat enters its second year it is a mature adult and if neither neutered or spayed will have sired or given birth to kittens
After it reaches two years of age, an indoor cat ages approximately four “human years” for every calendar year. Thus, a 5-year-old kitty is approximately 36 in human years.