How Do You Calculate Cat Years to Human Years?

If you live with a cat or have ever loved or cared for a cat, you have no doubt wondered about the comparison of cat years to human years. Is it true a two-year-old kitty is as mature as a teenage human? Or is it more likely that your five-year-old fluffy companion really has more in common with a senior citizen? Let’s explore.

How Do You Calculate Cat Years to Human Years?

It is repeated time and time again: cats have nine lives. Of course, this isn’t meant to be a literal statement, unless you are discussing Tom of the famed Tom and Jerry duo. Saying cats have nine lives means that they are little daredevils and always seem to land on their feet. One life or nine, there is still no clear consensus on how those lives compare to our lives in years.

an orange kitten baby playing on the beach

Cats are commonly known to have been close with humans as far back as 4000 years ago, as in they were considered to be goddesses. Cats back then had legal protection and were even more prominent than some humans.

Archaeologists have discovered now that cats lived among humans in Mesopotamia over 100,000 years ago and may have been domesticated there approximately 12,000 BCE. And as long as us humans have loved cats, we have wondered, figured, calculated, and guessed how their age compared to ours.

So how do you calculate cat years to human years? Keep reading below to learn some of the many ways.

What’s The Lifespan of The Average Cat?

Depending on the breed, a cat can be expected to live 13 to 17 years, averaging right about 15 years. This number has risen strikingly in the past 40 years. As recently as the early 1980’s, domesticated cats only lived about seven years, this increased to about 9 and a half years in the mid-1990’s, and now it’s up to 15-year average.

gray kitten

As records go, the oldest known cat to have been recorded was Lucy of Llanelli, Wales. Lucy lived to be an astonishing 39 years old (1972 – 2011).

More likely, we as feline lovers will enjoyour precocious pets for a very short amount of time relative to our ownlifespans. There are several factors that can affect a cat’s agedness.

Female cats usually outlive their malecounterparts, and those of us who pay top dollar for purebred felines might bedisappointed to learn that mixed breed mousers will most likely survive longerthan our pricey pussy-cats.

The main contributor to the increase in thelength of cats lives is possibly having them neutered. Even feralcats that are fortunate enough to be part of the “Trap-Neuter-Release” programsall across the country have comparable lifespans to their domesticated,neutered counterparts.

Why does this matter? Consider that malecats that have been neutered cannot get testicular cancer. Female cats thathave been spayed cannot get uterine or ovarian cancer, and both have a decreased risk of mammary cancer.

Cats versus Dogs

The old standard of “one dog year is equalto seven human years” has been updated. It is more common to discuss and figure“dog years” than it is to try to calculate cat years to human years. This could be contributed to the fact that dogs more commonly learn tricks and obey commands, so the comparison is easier drawn.

a cute brown kitten a cute brown puppy

Regardless if you are a dog person or a cat person, it is intriguing either way to know how our pet compares to us in the age category. Surprisingly to some, dogs are not the most popular pet for Americans.

Equally as surprising, neither are cats. That prestigious title goes to freshwater fish. Dogs come in a close third to cats, who make up the second most kept house pet in the U.S.

Cats, like dogs, mature much more quickly than humans do in the first few years of life. A two-year-old cat or dog is well equipped to live outside and could survive by itself if made to. Atwo-year-old human absolutely would not be able to do so.

But is a two-year-old dog equal to a two-year-old cat? It’s nearly impossible to say, but most schools of thought agree that cat ages slightly faster than a dog. For instance, a three-year-old cat is said to be comparable to a human of about 32, where a three-year-old dog is just about the same as a 28-year-old human.

Calculating Cat Years To Human Years

While there is no scientifically agreed upon method of calculating cat years to human years, the process of using average life expectancies is considered the most common practice. From there itis a basic mathematical equation:

kitten chasing a butterfly

H (human life average) / C (Cat life average) = Y (Cat years in human years).

How accurate is this equation, though? Ifwe were to fill in the data for the 1800s, for example, we would get:

35 / 6 = 5.8. So using this equation in1800 would mean cat years we about 6 for human years.

If we update it to a more modern standard, using the 1990s as the example we would then see:

72 / 9.5 = 7.5 cat years. Rounding up we would have 8 cat years per human year.

Again, going to the stats used today, just 20 years later we then see the formula work out like this:

80 / 16 = 5. So the formula shows that currently, cats live 5 years for every human year. However, in the time span covered by the formulas, humans, and cats are both living longer, and the difference between them goes up and down regardless of the life expectancy.

a happy old woman

This can be attributed to antibiotics, medical advances and the fact that humans have just more than doubled their average life expectancy while cats have almost tripled theirs. To be moreprecise, humans have near tripled the life expectancy of cats.

So how do we get an accurate number that seems to follow along with the advances in technology and medicine? That is a more difficult equation.

For that, you will need the average lifespan of each species, both male, and female, and then account for the difference in life expectancy of neutered or spayed cats and any otherconditions that affect both humans and cats for their longevity.

In essence, we would need to be able to accurately chart why males and females have different life expectancies as well as what cause those numbers to rise or fall. We would also have to account for the instances of indoor versus outdoor cats, geographical location and theirunderlying conditions.

For example, Humans have a longer life expectancy in Canada than they do in Europe or the United States. We don’t have the data to determine if cats live longer in each geographical location.

life cycle of a woman from baby to adult

With so many unknowns, it is near impossible to state a direct correlation, so we are left to guess. However, we can be a little more accurate with just a few more pieces of information.Without having to bother an MIT calculus professor, we can do this right here and now.

The first step is to separate the genders and compare males to males and females to females. We do this because in both species the female version has a longer life expectancy.

Next, we take into consideration the actual change in life expectancy over the course of 100 years, since before that we didn’t keep tabs on the cats as much, and this not only allows us to use 100 as a divisor but keeps the data period more manageable.

We will also use a single region of the globe for our formula, in this instance the United States, as the census records are more constant over this period than most other areas. Of course, this will also act as our discrepancy, where we can round up or down accordingly if your local area numbers are a little different.

Now we just have to input out data:

  • Human Male (HM) life expectancy (1920::2020) = 54::80
  • Human Female (HF) life expectancy (1920::2020) = 66::91

Therefore, our human life expectancy change would be:

  • HM = 26
  • HF = 25

Now the same for the cats.

  • Male (1920::2020) = 7::13
  • Female (1920::2020) = 8::15

The change then would be:

  • MC = 6
  • FC = 7

When we input the new numbers in our formula, we find that, on average, over the course of the last 100 years, male cats lived 4.3 years for every human male year, while female cats live 3.6years for every human female year.

When you take the rounded average for regional discrepancies, you will find that both males and females have a 4 to 1 year of life ratio.

Or, to put it another way, there are 4 cat years for every human year.

When you take the data and compare it to the long-standing “7 dog years” formula, you can see that it is pretty accurate, as cats tend to live about 3 human years longer than dogs, on average.

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