Cat Years to Human Years: History, Calculation, Facts & More

You've probably heard of the concept of cat years and dog years before. At first glance, it's a pretty simple idea, but there's actually a lot more to it that you might not expect. It's quite an interesting topic, so I thought I'd talk about it today!

What are Cat Years?

The idea of cat years is a way to balance the scale and think about our furry friends in their own context.

If you assume, for example, that a human lives to be about 80 years old, and you know that cats live to be about an average of 15 years old, you can create a scale. If you then divide up 1-15 into 80 individual segments, you can calculate how many "years" old a cat would be in human years.

A cat aged 15 years old would be the equivalent of 80 years old "in cat years," and so on.

The reality, though, is that this kind of scale doesn't actually work. Human development is initially slower, and cat development moves in leaps and bounds throughout their early life.

That means a cat that is only a month old can be in the 1-2 "cat years" old stage, and by the time they reach their first birthday, they're actually the human equivalent of about 15. By the time a cat is four years old, they're the human equivalent of 32 years old. But this isn't a linear scale. It's a little more complex than that.

How are Cat Years Calculated?

Cat years are calculated by taking their age in real years and adding some amount, plus the next year plus a number, and so on. It's kind of tricky, so most of the time, people present it as a chart.

As you can see, the age is somewhat frontloaded here; a kitten develops from the equivalent of a human newborn, to a human baby, to a toddler, to a grade-schooler, to a pre-teen, all in the first year or so of their life. After that, development slows down; they reach their adult stage and simply age as gracefully as they can. These cat life stages are something I go into in greater detail here.

You might notice that the numbers added to each stage alternate once they reach three real-life years old. This isn't really necessary; you can just add 4.5 each time instead of alternating 4 and 5. There are also other charts that estimate this differently, and use 3.5 instead or alternate between +3 and +4.

I've also seen estimates that cats age fifteen cat years in their first year, seven years in each of their next two years, and then four years for every following year.

All of this makes it pretty clear that cat years are made up. When all of the major pet resources have authoritative guides on cat year calculations, and they all have different calculations, it's pretty clear that it's not actually that important to get it all right.

Does this really matter? Not really. The truth is, cat years are mostly a made up fiction for we people to compare our kitties to, to say "look at my old man" while we pet our dozy and snuggly old boy while he naps in a sunbeam.

How Long is a Cat Year?

It varies! Cat years are basically just made up, though. So, there are a few different answers to this question.

The simple answer is that a cat year is the same as a human year. Cats don't experience the seasons any faster than we do, and 365 sundowns and sunrises make a year, no matter what species you are.

Another simple answer is that a cat year is around 4-5 human years, equivalent. Or maybe it's better phrased the other way around: a human year is the time it takes a cat to age 4-5 cat years.

When you factor in the table above, it's even more different. The first cat year is the most action-packed of all of them and crams in 15 years of development. The second is a much slower pace and is only a decade. After that, it settles into a rhythm of averages of four or five years each year.

While it's fun to calculate and think about, it's not really useful to think about cat years.

Are Cat Years Real?

Yes and no.

Cat years are as real as any other concept in human experience. We decided that a cat year has some meaning, and so cat years have some meaning, at least to us.

Our cats? They don't care. They take each day as it comes, they don't know, care, or celebrate birthdays, and the only attachment they have to time is their internal clocks telling them when it's time to be fed.

Woe betide you if it's daylight savings time and you set your clocks an hour different and you haven't adjusted feeding time to match.

Cat years can be "real" in that they give you some sort of expectation of the kinds of health concerns to anticipate for your cat. A cat reaching 12 years old might not sound that old from human experience, but they're well into their golden years as far as cat years are concerned, so you'd want to be watching for those signs of old age. Knowing if you should be watching for the signs of kitty dementia, for example, can be important.

Then again, if you're taking your feline companion to the vet for regular checkups, you don't really need a cat year calculation for that; they'll keep you apprised of what you should be watching for and what you should anticipate.

What Affects a Cat's Aging?

One of the biggest problems with cat years is that it's not really reflective of anything in reality. The truth is, a lot of different things can impact how long a cat lives and how long they maintain their youthful attitudes and energy levels.

Your cat's breed. The breed of cat can be impactful. Often, the more purebred the cat breed, the shorter the lifespan. Cats with some amount of wildcat in them can live longer. Larger cats can often live longer, though that's not always true. "Mutt" cats, like plain old everyday domestic shorthairs, are generally on the longer side of average.

The breed is also important because some breeds have genetic issues that mean they can be predisposed to certain diseases, especially in old age, that can lead to organ failure and an earlier passing.

Their weight. Obese cats have much shorter lifespans than cats in a healthy weight range. Obesity is a problem in cats, in people, and even in wild animals, and it's not an easy problem to solve. Weight maintenance is very important for the long-term health of your cat, and the longer they go in an overweight state, the more likely they are to develop problems related to it, including pancreas issues, diabetes, arthritis, and more.

Underweight cats also have shorter lifespans due to malnutrition, and they often have a harder time fighting off parasites and infections. Feeding cats properly is tricky but important!

Indoor versus outdoor living.Cats that spend all their time outdoors are, unfortunately, much more likely to die earlier. There are a ton of reasons for this: exposure to the elements, fights with wild animals and other cats, greater exposure to illness and parasites, less ability to be treated, less consistent food and water, less clean water, encounters with cars, encounters with evil people; the list goes on and on and on.

There's a reason there's a huge push these days to keep cats inside and to catch-fix-release strays and ferals to reduce the overall outdoor population. It's not good for local wildlife, it's not good for the cats, and it's not good for the people who have to deal with the repercussions of it all.

Food quality.Another factor in lifespan is simple food quality. The better quality the food – that is, the less filler in particular – the better off a cat will be. A balanced diet can be tricky and expensive to maintain, but the worse the food is, the harder it is to keep a cat going without running into obesity or other health issues. This is also another reason why keeping cats indoors is important; you can more easily control what they eat.

Checkups and treatments.Cats with regular veterinary care are going to live longer than cats without it. Whether this means keeping an eye on teeth, getting prescriptions for illnesses, diagnosing allergies and food sensitivities, or taking care of parasites, it's all part of the process.

Parasite exposure.Parasites might seem like they're something you can treat and get rid of, but the aftereffects can linger. Cats that get parasites might be at higher risk of developing long-term illnesses, including cancer, because of it. Even when the parasite is gone, the damage is not, and it can manifest years later.

How Can You Tell a Cat's Life Stage?

A cat's stage of life is fairly easy to evaluate. Are they young, small, and lanky? They're a kitten. Are they full-size but still relatively energetic? They're an adult. Are they full-size but sleepier? They're probably a senior.

You can read my guide to cat life stages for more detail.

For that matter, vets don't necessarily go by pure time for a cat's life stage. They can evaluate the overall status of a cat based on other factors as well. These can include:

• Size
• Weight
• Oral health
• Eye health
• Ear health
• Bodily condition
• Behavior
• Blood work results
• Physical examination results

All of these can help a vet determine how old the cat is, and give you some idea of how old they are in terms of lifespan. This can be useful if you're picking up a stray cat and considering adopting it; you might want to know about how old it is and how long it has left before you make specific long-term life plans.

You can tell the rough age of a cat by their teeth, too. Kittens get their first teeth in the first 2-4 weeks of life. Their baby teeth come in sharp and strong, but they only have 26 of them. When they get a little older, around 4-6 months, they'll start to lose those kitten teeth, and their adult teeth will grow in. They'll have 30 adult teeth. Senior cats, of course, might have lost some teeth over time, but you'll be able to tell whether or not a cat is a senior by other means.

You can also often tell that a cat is getting on in years when their fur coat starts to get some gray hairs to it, and it ends up a little more raggedy and a little less well-groomed. Older cats might not groom themselves as much, or they might focus more on certain areas and forget about others, so they can look a little scruffy.

What's the Best Cat Year?

All of them!

Whether you calculate your kitty's years in cat years or human years, the important part is to spend each and every one of those years caring for, playing with, loving, and enjoying your feline companion. For you, they may not be more than a decade of your life; for them, you are there with them their whole life. A good and bonded cat will love you with the whole of their being, and you can love them back just as strongly, no matter what timeline you use to calculate their age.

So, here we are at the end of this article! Do you have any questions about anything I mentioned in this article, or would you like any additional clarification on a specific part? If so, I'm always more than happy to help you out however I can. Just leave a comment down below, and I'll get back to you with a reply as soon as I can!