How to Convert Your Cat’s Age to Human Years

There’s the oft-quoted idea that about one dog year is equivalent to seven human years, but is the formula really that simple? The conversion formula for both dog and cat years to human years is actually much more complex. Because both of these animals mature at a faster rate than humans, the first years of your pet’s life actually equate to more human years than the subsequent years.

Your Cat’s Age in Human Years

Early Maturation: Your feline companion is your precious baby, we know, but you must remember that cats are still animals. They are still much closer to their wild roots than us bipedal humans.

A primary example of this is the way that humans have evolved to have long gestation periods and then even longer periods of intensive rearing and childcare. Domesticated housecats have a gestation period of only 66 days and give birth to kittens that require just a small portion of the kind of attention and care that human babies require.
That’s why a one-year-old kitten is developmentally equivalent age of a 15-year-old human, and the physical maturity of a two-year-old cat is roughly equivalent to a 25-year-old human. Then, for each year after the first two, equate each cat year to about four human years. That would make a 5-year-old cat about 37 human years old.

An Alternative Formula: Tracie Hotchner, author of The Cat Bible, offers a slightly different variation on the aforementioned calculation. In this alternative formula, Hotchner delves more specifically into the corresponding ages of young kittens to similarly young human children. Here, courtesy of Hotchner, is the answer to the question, “How old do cats live in human years?”

  • 1-month-old kitten = 6-month-old human baby
  • 3-month-old kitten = 4-year-old child
  • 6-month-old kitten = 10 human years old
  • 8-month-old kitten = 15-year-old human
  • A 1-year-old cat has reached adulthood, the equivalent of 18 human years
  • 2 human years = 24 cat years
  • 4 human years = 35 cat years
  • 6 human years = 42 cat years
  • 8 human years = 50 cat years
  • 10 human years = 60 cat years
  • 12 human years = 70 cat years
  • 14 human years = 80 cat years
  • 16 human years = 84 cat years

Two Ways to Look at Age: Though the common perspective on cat years and human years is trying to figure out how old our cats are in human years, that conversion can be applied both ways.

That is to say, if you consider the maximum age of a human to be 100 years, then, based on the Cat Calculator, the maximum age of a cat is 20.8 years. On the other side of the coin, if you consider that, as The Cat Bible suggests, 16 human years is comparable to 84 cat years, then a 100-year-old human could be said to be the equivalent of 525 cat years.

Though this is a generally less practical way to consider the relative aging rate, it does serve as an important reminder. The way we experience time, the length of our human years, and the meaning we assign to certain-numbered years (the big 3-0, for example), is a matter of perspective. Some other oft-quoted ideas come to mind: It’s not the years in your life, but the life in your years and You’re only as old as you feel.