Cat years to human years — it’s one of the hottest debates in the cat community right now. Some cat experts will tell you that one cat year is equal to seven human years, but others swear that the 15-9-4 rule is the more accurate way to go. So, who’s right?
Since calculating cat to human years isn’t an exact science, there’s no real right or wrong way to do it.
There is, however, an easy and an elaborate way to calculate your cat’s age in human years.
Why Some Experts Avoid the 7-Year Rule
The 7-year rule — where one cat year equals seven human years — is as simple as it gets, but it’s not fully indicative of how a cat ages. That’s because a cat’s natural aging process tends to vary over their lifetime and doesn’t perfectly match up with the way humans age.
For example, most cats are considered an adult by the time they turn 18 months, which would make them about 10 in human years, according to the 7-year rule. Yet, it takes humans 18-21 years to achieve adult status — so the 7-year-rule is a bit off in that regard.
Furthermore, cats are considered seniors after they turn 10 years old, according to the American Association of Feline Practitioners (AAFP), which would make them 70 years old.
Most humans are considered a senior by the age of 60 or 65 — again, the 7-year rule is close, but a little off.
Introducing the 15-9-4 Rule
It’s impossible to be perfect when converting cat years to human years, but the 15-9-4 rule offers a much more accurate depiction of that comparison.
To reflect your cat’s fast development, the 15-9-4 rule states that the first year of the cat’s life is equal to 15 human years and the second year is equal to nine human years – making them 24 years old after year two.
For each year after that, one cat year equals four years. So, they’ll be 28 after year three, 32 after year four, 36 after year five and so on…
Following this model, a cat would be considered an adult around the age of 20 (18 months in cat years) and considered a senior at 60 years old (10 in cat years).
Why Do People Convert Cat Years to Human Years?
The reasoning behind calculating a cat’s age in human years differs for each individual. For example, some people might tell you they find it interesting to think about, while others might use it as a way to better understand their cat’s aging process.
After all, most of us understand what happens as we age and your cat will go through a lot of the same things — albeit at different times (hence, the need for the conversion).
Their vision worsens, they lose muscle mass, they become less active and they often lose weight — all things that happen to us as we age.
At the end of the day, converting your cat’s age to human years is just another way to bond and connect with your cat as you grow together!
What’s the Average Life Expectancy for Cats?
The average life expectancy for cats depends on a wide range of factors, including the cat’s breed, genetics and overall health. But nothing has a greater impact than whether it lives indoors or outdoors.
Most indoor cats will live to be between 15 and 18 in cat years (or 76 and 88 in human years), but some lucky owners will see their cat live longer than that.
Unfortunately, outdoor cats are known to live a rather short life with most struggling to live beyond five years. So, how does that compare to humans?
As of 2022, the average life expectancy of a person living in the U.S. is 77.5 years old — including 74.8 years old for males and 80.2 years old for females.
In other words, raise an indoor cat if you want your cat to live a full life.
What’s the Oldest Cat Ever Recorded?
The oldest cat to ever live was a cat named Creme Puff, who died three days after its 38th birthday, according to the Guinness World Records.
To put that into a human perspective, Creme Puff was 168 years old in human years when she died.
Jeanne Calment is the oldest known human, having lived to be 122 years old — which means Creme Puff was 46 human years (or about 11 cat years) older than the oldest human.
Creme Puff was born on August 3, 1967, and passed away on August 6, 2005. She lived with her owner, Jake Perry, who was also the owner of Grandpa Rex Allen — the previous record holder.
How Old Is the Oldest Living Cat?
According to an article by The Guardian, the oldest living cat is named Flossie and she lives in London, England. Flossie celebrated her 29th birthday in cat years on Dec. 29, 2024, according to her owner, Nicki Green, who just so happens to be the same age.
“At the time, I thought it was an error and that she must be 17,” she recalled of the day she adopted Flossie.
“Cats Protection told me she was still available to adopt and that no, she was in fact 27, the same age as me. It is weird to think that Flossie and I were born in the same year,” she continued.
To put Flossie’s age into perspective, she’s currently 132 in human years, as of 2024.
Are Dog Years Calculated Any Differently?
Much like cats, there’s an old adage that says one dog year is equal to about seven human years. But as we learned above, that’s not a very accurate way to do things — and that’s true with dogs, too.
With that said, the American Kennel Club has a slightly different way of looking at a dog’s age. Instead of the 15-9-4 rule, they follow a 15-9-5 rule for most small- to medium-sized dogs.
The main difference with dogs is that they can be anywhere from 20 pounds and less to 100 pounds and more — so the conversion largely depends on what type of dog you have.
But we can save that topic for another day.
