What is a cats age compared to humans

You’ve probably heard that one dog year is equivalent to seven human years, but is the formula really that simple? The conversion formula for both dog and cat years to human years is actually much more complex. Because both of these animals mature at a faster rate than humans, the first years of your pet’s life actually equate to more human years than the subsequent years. To get a better idea of how cat and human ages equate, use our cat age calculator:

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Your cat's age in human years

Early maturation

Your feline companion is your precious baby, we know, but you must remember that cats are still animals. They are still much closer to their wild roots than us bipedal humans.

A primary example of this is the way that humans have evolved to have long gestation periods and then even longer periods of intensive rearing and childcare. Domesticated house cats have a gestation period of only 66 days and give birth to kittens that require just a small portion of the kind of attention and care that human babies require. And the little bit of work they do require can be done with a self-cleaning litter box.

That’s why a one-year-old kitten is the developmentally equivalent age of a 15-year-old human, and the physical maturity of a two-year-old cat is roughly equivalent to a 25-year-old human. Then, for each year after the first two, equate each cat year to about four human years. That would make a 5-year-old cat about 36 human years old.

If you’re having trouble grasping early maturation in cats, look at this way: Kittens do most of their growing in the first 6 months of life. In fact, healthy kittens grow 8 times their size in just about 8 weeks! By approximately 1 year old, cats will weigh at or around their adult weight, which typically ranges from 7 to 15 pounds depending on the breed. 

How do you know when your cat has stopped growing? Most veterinarians agree that your cat is done growing between 9 months and 2 years old. However, some breeds take years to fully mature.

An alternative formula

Tracie Hotchner, author of The Cat Bible, offers a slightly different variation on the aforementioned calculation. In this alternative formula, Hotchner delves more specifically into the corresponding ages of young kittens to similarly young human children. Here, courtesy of Hotchner, is the answer to the question, “How old do cats live in human years?”

• 1-month-old kitten = 6-month-old human baby
• 3-month-old kitten = 4-year-old child
• 6-month-old kitten = 10 human years old
• 8-month-old kitten = 15-year-old human
• A 1-year-old cat has reached adulthood, the equivalent of 18 human years
• 2 human years = 24 cat years
• 4 human years = 35 cat years
• 6 human years = 42 cat years
• 8 human years = 50 cat years
• 10 human years = 60 cat years
• 12 human years = 70 cat years
• 14 human years = 80 cat years
• 16 human years = 84 cat years

Cat years to human years: The indoor vs outdoor factor

If you used our cat years to human years calculator above, you might be wondering why you had to specify whether your cat is indoor-only, outdoor-only, or a mix. The sad fact is, a cat’s environment largely influences their lifespan. Ask any veterinarian and they’ll tell you: Cats that go outside are more at risk of harm or injury.

Just as ancient man lived outdoors and had a life expectancy of 20-30 years, outdoor cats face exposure, predators, harsh conditions, and chronic “wear and tear” that can ultimately lead to a shorter life expectancy. Indoor cats are the modern equivalent of pampered, sheltered royalty when compared to outdoor cats or even indoor/outdoor cats.

Speaking of indoor/outdoor cats: Even if 90-95% of your cat’s life is indoors, your veterinarian still needs to know about the small percentage of time spent outdoors. Why? Because it affects how they care for your cat and what diagnostics, vaccines, medications, and treatment they may use.

So, why is a 5-year-old indoor cat in the prime of his life (36 years old in human years) while a 5-year-old outdoor cat has already entered middle age (48 years in human years)?

Why outdoor cats “age” faster

There’s a difference between an outdoor cat with no home (i.e. feral or stray), and a cat with a loving home that just happens to live outside. The former’s lifespan is adversely affected by lack of vaccinations and routine vet visits, as well as not being spayed or neutered. But even if your outdoor cat is vaccinated, sees the vet regularly, and is spayed or neutered, there are still a lot of risks with living outside.

First, being outside poses trauma dangers. Your cat might get hit by a car, attacked by a dog or coyote, injured by the neighborhood bully, or beat up by the neighborhood tomcat. Veterinarians report trauma as the #1 issue seen in a veterinary ER with indoor/outdoor cats. Trauma can result in fractures, lung bruises, internal bleeding, and even death. And if you’re lucky enough to save kitty’s life, treatment may cost several thousands of dollars for repair. 

Next, being outside poses poisoning dangers. Something as simple as your cat eating your neighbor’s tiger lilies or daylilies, digging around and finding some mouse poison, or accidentally being exposed to antifreeze in your neighbor’s driveway can result in death. 

Finally, the outdoors pose infection or disease transmission risks that can potentially be fatal to your cat. Fighting with other cats can easily result in your cat getting the blood infection feline leukemia (FeLV) or kitty AIDS/FIV. Also, if your cat goes outside, the risks of tapeworms, fleas, ticks, and other parasites dramatically increase. It’s extremely important that your outdoor cat be vaccinated and up-to-date on their FeLV and rabies vaccines, along with year-round flea, tick, and heartworm medication. 

Two ways to look at age

Though the common perspective on cat years and human years is trying to figure out how old our cats are in human years, that conversion can be applied both ways.

That is to say, if you consider the maximum age of a human to be 100 years, then, based on the Cat Calculator, the maximum age of a cat is 20.8 years. On the other side of the coin, if you consider that, as The Cat Bible suggests, 16 human years is comparable to 84 cat years, then a 100-year-old human could be said to be the equivalent of 525 cat years.

Though this is a generally less practical way to consider the relative aging rate, it does serve as an important reminder… The way we experience time, the length of our human years, and the meaning we assign to certain-numbered years (the big 3-0, for example), is a matter of perspective. Some other oft-quoted ideas come to mind: "It’s not the years in your life, but the life in your years" and "You’re only as old as you feel."

How old is your cat according to the cat years to human years formula? Or perhaps we should ask, how old are YOU in cat years?

Photo by Manja Vitolic on Unsplash

If your cat is a rescue, you’re bound to find yourself wondering How old is my cat? While the number may not matter, having some idea of your cat’s age (from cat years to human years) can help you anticipate their needs and provide them with everything they require for a healthy and happy life. 

Below you’ll learn how cat’s age in relation to humans, simple tips for honing in on your cat’s age, the signs of a senior cat, how long cats live, and what you can do to help ensure your cat lives a long life at your side. And while you’re here, check out how to keep outdoor cats safe. 

Table of contents

It’s commonly stated that one human year is the equivalent of 7 cat years. This is an effort to demonstrate that cats age more quickly than humans. However, they do not age proportionately.

Cats reach maturity at a much faster rate than humans in the beginning of their lives. Once they reach adulthood, their aging slows down.

It’s difficult to draw a direct comparison between a cat’s age and its human equivalent, but the general consensus is that a cat ages the equivalent of 15 human years in the first year of their life.

By the end of their second year, a cat is thought to be the equivalent of 24 or 25 human years.

From 2 years on, experts believe cats age at a rate of approximately 4 human years per cat year. 

Cat years chart: Cat years to human years

Keeping track of your cat’s aging can be confusing, so we’ve created this handy chart to help you convert cat years to human years. Understanding how old a cat is in human years can help you understand their current life stage and better predict their needs. 

How to tell how old a cat is if you don’t know when they were born 

Even if you can’t be sure when your cat was born, it’s still possible to determine their age with relative accuracy. The state of your cat’s teeth, coat, muscle tone, and eyes all offer insight into their age.

Using the tips below, you can work to identify your cat’s life stage and then make an educated guess as to exactly how old your cat is. 

How to tell a cat’s age by their teeth

A cat’s teeth can be telling when it comes to determining their age. Adult cats have 30 teeth, while kittens have 26 baby teeth (also known as deciduous teeth).  

Kittens develop their first teeth between 2 and 4 weeks of age. By 6 weeks of age, kittens should have all of their deciduous teeth. Between 4 and 7 months of age, the deciduous teeth are replaced by adult teeth.  

Counting a cat’s teeth is a good place to start when trying to gauge their age. Once you determine whether the cat is a juvenile or an adult, you can use other characteristics to further narrow in on their age.

The color of a cat’s teeth and the amount of tartar present can also help indicate how old they are. Cats between 1 and 2 years of age often have some yellowing on their teeth, but tartar buildup should still be minimal. Beyond 3 years, you may see tartar buildup around the base of each tooth.

This is not a perfect science though, since cats with excellent dental hygiene will not exhibit much tartar, regardless of age.

Dark stains on a cat’s teeth or missing teeth could be indicative of a senior cat (one over 11 years old). 

What a cat’s coat says about their age

As cats age, their coats often begin to show some gray. In cats with light-colored coats, this change may not be noticeable, but for cats with dark coats, you’ll begin to see some grey or white hairs where there weren’t any before.

Older cats may begin to neglect their frequent grooming routines, leaving their coat looking dirtier or duller than it otherwise would. 

It’s not uncommon for a cat’s fur to change texture as they get older. The fur may become thinner, less glossy, or more coarse. Sometimes these changes can be indicative of a health issue, such as kidney problems or malnutrition, so if you notice sudden changes, don’t hesitate to contact your veterinarian. 

Muscle tone – another cat aging factor

Muscle tone is another indication of how old your cat is. Kittens are typically quite lean and have not yet accumulated much muscle mass. Healthy adult cats typically have good muscle tone. They shouldn’t have protruding bones, and their spine should be straight. 

As cats enter their senior years it’s not uncommon for them to begin losing muscle. You may notice your senior cat’s shoulder blades or hip bones begin to protrude more than they did previously. Often, senior cats aren’t as active as they once were (perhaps due to the aches and pains of aging) and thus they spend more time sleeping and less time exercising. Naturally, this leads to a loss in muscle definition.

While some muscle loss is normal, excessive muscle loss could be an indication of a serious health issue. Cats with poor nutrition or health problems such as kidney disease could struggle to maintain body weight and muscle tone. If you notice a sudden, significant decline in muscle mass in your aging cat, speak to your veterinarian. 

Cat’s eyes and the aging process

Clear, bright eyes are a sign of a young cat. As cats age, they may develop cataracts or glaucoma, leading to discoloration or cloudiness of their eyes. Senior cats often have more eye discharge than a kitten or adult cat. Sometimes a cat’s irises will change shape too, beginning to look jagged around the edges rather than smooth.    

How do cats age?

As you can see in the chart above, cats undergo the biggest age-related changes in the first couple of years of their lives.

By the end of year one, cats are said to be comparable to a 15-year-old human. Within this period, a cat goes from a newborn kitten with closed eyes and no teeth to a young adult cat who has reached sexual maturity. 

Cats are said to age approximately 9 human years in their second year of life, making them the equivalent of a 24-year-old human by the time they are 2 years old. 

Two-year-old cats have reached sexual maturity, and they have stopped growing. By this time they have accumulated muscle mass and are settling into their adult physique. 

After two years, cats age more gradually, at a rate equivalent to about 4 human years for each cat year.

Once cats reach about 11 years old they are considered senior citizens. They are now the equivalent of a 60-year-old human. Around now, your cat may begin to show signs of aging, such as a decline in physique, graying fur, and changes in their eyes, teeth, and coat. 

Senior cats continue to age at a rate of about 4 human years per cat year. 

Signs of a senior cat 

Just like in humans, there are some tell-tale signs of senior status among cats. While senior cats are often still healthy and full of life, they may begin to slow down a little. As your cat transitions into senior status, it’s important to take note of any changes as drastic shifts could be indicative of serious health conditions.  

Senior cats may exhibit:

• Stiffness and decreased mobility
• Cloudy eyes
• Dull coat
• Excessive eye discharge
• Weight loss and loss of muscle tone
• Frequent urination
• Confusion or disorientation

Beyond physical decline, senior cats may also exhibit dementia. Some common signs of feline dementia include frequent meowing, disorientation, and excessive sleeping.

Senior cats can still have many wonderful years ahead of them, so don’t be discouraged or distraught if your cat is starting to slow down. Simple lifestyle tweaks, such as specially formulated food can help your senior cat make the most of their twilight years.

How long can cats live? How long do cats live on average?

Cats have an average life expectancy of 16 to 18 years, though some cats may live even longer. In fact, according to the Cornell Feline Health Center, many cats live to be 20 or 21. 

Certain cat breeds are known to have notably long life expectancies while some are more susceptible to certain health issues than others. For instance, both Siamese and Savannah cats are said to have a life span as long as 20 years. Meanwhile, Ragdoll and Persian cats are both susceptible to Polycystic Kidney Disease (PKD). 

According to the UC Davis Department of Veterinary Medicine, indoor cats are expected to live much longer than outdoor cats. This is largely because indoor cats face fewer hazards than cats who live outdoors. Outdoor cats are vulnerable to threats like predators, traffic, toxins, and diseases from other animals that indoor cats may never come into contact with. Keep outdoor cats safe with these tips.

Of course, nothing is ever guaranteed. Even indoor cats that are extremely well cared for may fall ill unexpectedly, while breeds that are highly prone to certain health afflictions may never be affected by them. As frustrating as it may be, there’s just no way of knowing how long your cat will live. 

Feeding your cat a balanced diet and ensuring they maintain a healthy body weight can help increase your cat’s life expectancy and keep them agile and active well into old age.  

How to make your cat live longer? 

Naturally, we all want our pets to live forever. While we can’t promise this, there are simple things you can do to help ensure your cat lives a long and fruitful life.

Just as with humans, diet and exercise are a big part of your cat’s longevity. They are also two of the few aspects you have control over. 

Feeding your cat a high-quality, balanced diet will help them stay healthy and happy throughout each stage of their life. And keep in mind that as cats age, their dietary needs change. So speak to your vet about how to provide the best nutrition for your cat in their current life stage. 

Moreover, physical activity is also essential for good feline health. You may decide to let your cat outside for this reason. In this case, a Tractive GPS Cat Tracker can be a lifesaver. The cat tracker not only shows you where your cat is at all times, but also allows you to see how much physical activity they get. These insights can help you notice any changes in your cat’s habits, allowing you to swiftly address abnormal behavior and make any necessary lifestyle tweaks.

With these tips, you’ll be able to determine your cat’s age and provide them with everything they need to thrive during this stage in their life. 

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