orange and white cat laying by window next to plant, not worried about their cat age in human years
orange and white cat laying by window next to plant, not worried about their cat age in human years

Calculating Your Pet’s Age in Cat Years

Pass a group of children on the street, and it isn’t hard to figure out whether they’re 4 or 14 years old  — humans have distinct developmental stages that make it easy to separate a preschooler from a high school freshman. But with cats, warp-speed physical and behavioral changes can make it feel almost impossible to determine their age relative to a human’s.


Pinpointing your cat’s developmental stage relative to their age can be a big help in caring for your pet as they grow and mature. Fortunately, calculating their developmental age in “cat years” isn’t complicated (though it’s not as simple as the “7 cat years for every calendar year” formula you may have heard about). Don’t worry — these calculations won’t be on the test, and you can always come back to our cat age chart below to check your work.


Cat Age Chart: Calculating Age in Cat Years (+4 cat years for every calendar year)
Life Stage Cat’s Actual Age Human Age Equivalent
Kitten 12 months 3 months 6 months 0–1 year 4 years 10 years
Junior 12 months 18 months 2 years 15 years 21 years 24 years
Prime 3–6 years 28–40 years
Mature 7–10 years 44–56 years
Senior 11–14 years 60–72 years
Geriatric 15+ years 76+ years


Guidelines developed jointly by the American Animal Hospital Association (AAHA), the American Association of Feline Practitioners (AAFP) and International Cat Care.



Cat Age Is Just a Number ... Plus Another Number

You don’t need to be an expert to calculate your cat’s age, just use the “15-9-4” rule: 15 cat years in the first calendar year and nine in the second before leveling out to a rate of four cat years per calendar year for the rest of their life. That’s the quick calculation; now let’s break down what the phases of your cat’s life look like and how their needs may change over time.


The Many Ages of Your Cat’s First Year 

As you already may have guessed, the first year of a cat’s life sees the fastest rate of change. Vets and other feline specialists generally agree that the first year of a cat’s life is equivalent to 15 cat years. That means your little kitten grows from a cooing baby into a swaggering teenager in just 12 whirlwind months. (And you thought your nephew was growing up fast!) Pay close attention to your kitten’s health during this rapid growth, and don’t be shy about calling the vet if you have a question.


The Terrific Twos 

Year two isn’t far behind in terms of changes, packing an impressive nine cat years into one trip around the sun. During this time, your cat settles into their adult body complete with new adult behaviors. You may notice they seem less curious or clumsy, and perhaps a little more authoritative. Young adult cats tend to engage in less social play or cuddling. They’ll often begin to test physical and social boundaries, like going on longer solo expeditions or asserting their place in the feline hierarchy of a multicat household.


Steady As She Grows 

Once your cat enters their third year, changes become slower and steadier and our calculations get even easier. From the start of the third year onward, for every calendar year that passes simply add four to find their age in cat years.


Grown Up, Settling Down

In your cat’s adult and senior years, you’ll probably spot changes in their appetite, appearance and energy level. You can keep an eye on their overall health during these changes by checking their C.A.T.S. — Coat, Appetite, Temperament and Size. By this point, your furry friend is no longer growing like a weed, so they’ll need less food. A smaller appetite coupled with greater comfort and familiarity within their environment may also lead to noticeably lower energy levels. Practically, that may look like more time spent lounging on the sofa instead of turning somersaults on the cat tree.


Your Cat’s Golden Years 

When cats reach 15 or even 20 years of age, it’s important to continue to provide a high-quality diet, healthy environment and regular vet checkups. You’ve already done a great job helping your cat live a long, healthy life! Now your biggest role as a pet parent is to make sure your senior cat feels comfortable and loved.


What If I Don’t Know My Cat’s Birth Year? 

Cats don’t typically come with a manufacturer’s label, which can make it tricky to nail down your adopted or rescued cat’s birthday. Without a clear date of birth, how can you tailor your care to your cat’s age?


Fortunately, figuring out a cat’s age is pretty straightforward for your veterinarian. After that, routine visits to the vet — especially as your cat starts to show signs of aging — will provide regular opportunities for a licensed professional to chart changes in your cat’s condition and begin any necessary treatment.




Understanding your cat’s development by calculating their age in cat years can help you provide balanced nutrition, a healthy environment and the appropriate medical care they need. The “15-9-4” rule is there to help you remember: Cats develop extremely quickly early in life (15 cat years in their first calendar year and 9 in their second) before sticking to a rate of 4 cat years per calendar year. All those cat naps make a lot more sense now.

orange and white cat laying by window next to plant, not worried about their cat age in human years
orange and white cat laying by window next to plant, not worried about their cat age in human years
orange and white cat laying by window next to plant, not worried about their cat age in human years
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