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How to Convert Cat Years to Human Years (Based on Science)

american shorthair cat kissing her kitten

“Cat years” are a measuring system for how old a cat is in human years. It’s common knowledge that cats have a much shorter lifespan than humans, about 10–13 years. However, that stat is based on human years, which means you need to know how old your kitty is in human terms to fully understand their remaining lifespan.

If you have adopted a new feline friend or perhaps you adopted your previous cat when they were just a kitten, you might be wondering how old they are in human years. The good news is that this calculation isn’t as complicated as it might seem. You just need to know the right formulas! Here are a few tips on converting cat years to human ones.

divider-catCheck Your Kitty’s Age Before You Crunch the Numbers

Before you start calculating your cat’s age in human years, you need to know the cat’s age. You can do so by looking at the date of birth on the adoption papers that you received from the shelter. If you don’t have that paper, you can check the microchip ID or visually inspect your feline friend to get an accurate estimate.

There are a few physical traits that can help owners determine the proper age of their pet. For example, when a kitten is around 3 months old, their baby teeth will fall out and be replaced with permanent teeth. You can also take your cat to the vet and have them do a blood test. The vet will be able to determine your cat’s real age based on the bloodwork.

playful cat playing with crumpled paper balls on office desk in sunlight
Image Credit: Bondar Illia, Shutterstock

Difficulties in Converting Cat Years to Human Years

It’s possible you’ve heard that 1 human year is equivalent to 7 cat years. The same is said for dogs. While this calculation is close to accurate over the entire lifespan of your pet, there are a few problems with it.

The American Animal Hospital Association (AAHA), International Cat Care, and the American Association of Feline Practitioners have agreed upon basic guidelines for identifying your cat’s age in human years:

  • Year 1 of a cat’s life is equal to about 15 human years.
  • Year 2 of a cat’s life adds an additional 9 years.
  • After the second year, each year is equal to about 4 human years.

Find Out Your Kitty’s Age in Human Years

Using hat standard for cat aging, it’s relatively easy to calculate your cat’s age in human years.

Cat Age Human Age in Years
1 month 1
3 months 4
6 months 10
12 months 15
18 months 21
2 years 24
3 years and up 28 +4 years for every additional year
11 years and up 60 +4 years for every additional year

white and gray kitten on couch
Image Credit: Tran Mau Tri Tam, Unsplash

How Cats Age

The common misconception that 1 cat year equals 7 human years is misleading. Cats age quickly during their first 2 years of life, then slow down as they age. But how did we get this set of guidelines for converting cats’ ages to human years?

The AAHA states that its cat aging guidelines are based on behavioral and physical changes that occur throughout a cat’s lifespan. These stages are matched to the same stages in humans. Put in simple terms, a 1-year-old cat is at the same developmental level as a 15-year-old human. While both species undergo similar stages of growth and development, they do so on different timelines.

divider-cat

Final Thoughts

Cats age much faster in their first 2 years of life than they do later. By the time that your cat is 2 years old, they have reached the same developmental level as a 24-year-old human! After this point, they age at a rate of approximately 4 human years per year. Our handy chart here can help you calculate your cat’s age if they are young. For older cats, simply add 4 to every year to calculate their age.


Featured Image Credit: ANURAK PONGPATIMET, Shutterstock

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