Is One Cat Year Really Equal to Seven Human Years?

Posted on 30 Nov 2015 22:03 by EricT

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We often measure pet years in human terms, especially when it comes to our dogs or our beloved cats. It is an easy heuristic to help us understand the life expectancy of our cat. The most frequent way of stating this rule of thumb is that "seven cat years equals one human year."

Is this accurate? According to the rule, this would mean that a 2-year-old cat is equivalent to a 14-year-old human.

A 12-year old cat, then, would be equivalent to a 168-year old human! Since domestic cats routinely live to 12 years and beyond, out cats are suddenly seeming long-lived, indeed.

How Long Can Cats Live?

Believe it or not, there have been domestic cats that have lived to 20 to 22 years. In fact, during my employment as a veterinary technician, 20-year old cats were not that unusual. Cat's even live beyond two decades. There has been reported at least some 34-year old cat. Do the math. This cat was "biblical" in terms of its lifespan.

Although I am not sure about the record for the oldest domestic cat, a British cat named Puss is often said to have been the oldest cat on record. Puss dies in 1939 at the age of 36.

To tease this out, we have to understand the difference between a domestic cat and a "feral" or outdoor cat. The life expectancy of a cat that is not domesticated is around 2 years. Now, suddenly, the math seems to make sense. Outdoor cats are quite able to take care of themselves, but they face many hazards. Disease, accidents. Even poisoning.

And the environment the cat lives in, of course, affects its life expectancy. A wise old country cat will probably outlive his unfortunate city-slicker cousins, especially if he associates himself with humans, at least in a peripheral way. And even cats that don't quite trust humans are often intelligent enough to see the benefits of sticking close to a human habitation.

The question we would ask are, how much does the cat get to eat? What is the quality of the food consumed? Outdoor cats do not have a steady food supply and depending on the food available in the environment and its quality, a cat will live for fewer years, and may even starve to death.

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What are the hazards the cat faces in his or her environment? Are there predators? Cars? What about the weather? Clearly, there are to many factors that influence the feline lifespan to easily come up with a human-related mathematical lifespan formula.

Another thing to think about is that all cats do not behave the same was as they grow older. You may have had a pet cat who spent his waning years lying around and relaxing. You may have also known other cats of the same age who remained active and agile. Even displaying occasional "kitten-like" behavior. Cats are individuals.

Can Cat Age Be Measured in Human Terms?

So, what does science tell us about a cat's lifespan? And, is it possible to relate the average feline lifespan to human years? Yes, sort of. But, its much more complicated than the 7-year formula, which, as should be obvious by now, is a myth.

How Do You Measure Cat Years?

Although estimates may vary, cats reach adulthood between 18 and 24 months of age.

Humans reach adult-hood at around 20 to 22 years of age. I think many of us would agree that boys take longer, bringing down the average!

Therefore, if we equate cat years to human years, a cat who is one-year old is around 16 years of age in human years. But, before you decide adopt a 16/1 ratio, this only works for the first year. The next year equals to about six human years. Hence, we reach 22 human years.

Then, things get easier. You can add four human years to each cat year after the second year. For example:

  • A three-year old cat equals to a 26-year old human
  • A four-year-old cat equals to a 30-year old human.
  • A five-year old cat equals to a 34-year old human.
  • A seven-year old cat equals a 42-year old human.
  • An eight-year old cat equals to a 46-year old human.
  • A ten-year old cat equals to a 54-year old human.
  • A 12-year old cat equals to a 62-year old human.
  • A 14-year old cat equals to a 70-year old human.
  • An 18-year old cat equals to a 90-year old human.
  • A 20-year old cat equals to a 94-year old human.

Now, this may seem as if it does not add up. This is because we may also equate the human aging process to the cat's aging process. Cats, simply speaking, to not age exactly like humans.

Again, the formula given varies with the source, at least by a few years. Some vets will tell you that one cat year is equal to 15 human years. Then, a two-year old cat is approximately equal to a 24-year old person. We add two years the year after this, and then we add four years for each subsequent year. This makes a 20 year old cat roughly equivalent to a 96-year old person. As you can see, it really doesn't make a big difference as we can't really say too much about the difference between someone aged 94 and someone aged 96.

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