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Group of cats outside

The essentials

  • Determining cat age isn’t a science — However, scientific observation can give you a pretty good idea of how old your cat is.
  • Outdoor cats age faster — From threats to their safety and a lack of adequate nutrition, outdoor cats tend to age faster than their indoor counterparts.
  • Genetics play a role — Congenital conditions can impact how long your cat lives and what other conditions may develop throughout their life.

You’ve probably wondered several times yourself: just how old is your cat? While numerous factors go into how quickly cats age, it’s thought that indoor cats age about four years each year. Outdoor cats, which typically have less access to vet care, nutrition, or safety, age about eight years every year. Routine vet visits can help your cat have a long, happy life, along with being prepared!

The cat year to human years conversion

Is your cat a youngster or distinguished senior feline?

Your Cat’s Age in Human Years
Read more about cats and how to care for them here.

Deciphering your cat's age

Like dogs, it can be challenging to determine a cat’s age. There are few ways that your or your vet can determine how old your cat is.

Look at their teeth

Cats that don’t yet have teeth are less than four weeks old. Your cat’s 26 deciduous teeth (also called baby teeth or milk teeth) begin to come in at around two to four weeks. As early as 10 weeks, kittens will begin teething as their 30 permanent adult teeth start coming in. By six months, cats will have lost all of their baby teeth and have a full set of adult teeth. If your kitten is still developing, it’s important to watch for retained baby teeth .

In cats, looking at teeth during their first year of life can be helpful in determining their age at specific points. For example, at 4 months of age, most cats develop their permanent front teeth or incisors. At six months of age, most cats will have just developed their permanent canine teeth. There may be slight variation in some breeds in regards to development of teeth, but not enough to be considered significant.

Dr. Dwight Alleyne

If your cat has all of their permanent teeth, your vet will look at tartar buildup and the overall dental health of your cat. This isn’t a hard science — dental additives and diet can impact your cat’s oral health, aging their teeth prematurely, or keeping them in unusually good shape. For pet parents who aren’t sure about their new cat’s history, here are some signs to look for.

  • Streaks. Look for dark streaks down your cat’s fangs. This is plaque buildup in the crevices of their canines.
  • Discoloration. Typically more noticeable towards the root, look for brown discoloration on all of your cat’s teeth.
  • Red, inflamed gums. While not tartar buildup, red and inflamed gums can indicate gingivitis. This alone isn’t a determination of age, but it can help.
Cat with inflamed and red gums

Lastly, your vet will also look at overall wear and tear. As cats age, the enamel on their teeth will show signs of wear. Just like us, they can chip teeth, or damage the enamel due to food or play. Cats use their mouth to communicate and learn, so it isn’t a surprise that teeth can show a lot of wear and tear as cats age.

Check their coat texture, color, and thickness

As cats age, their coat changes as well. Kittens often have a shorter, fluffy coat that they will shed by the time they are a year old. As cats develop their adult coat, their markings may become more prominent and their coat glossier.

As cats age, their coat may become thinner and more coarse as they experience change. Cats also develop gray and silver hair (just like we do) with age. It’s important to keep in mind that dietary changes or health conditions can impact your cat’s coat too, so this alone isn’t a determination of their age.

Some cats experience changes in their coat due to temperature. Cats with darker “points,” like Siamese cats, can become temporarily darker during colder months due to a genetic mutation. This is a harmless and often beautiful seasonal change.

Gaze into their eyes

While any cat owner can be mesmerized by their cat’s kaleidoscope-like eyes, it’s important to look at them objectively. Kittens are born with blue eyes and at around eight weeks, their eye color will change into the one that will be with them (more or less) throughout their life. Additionally, younger cats have brighter, clearer eyes than older ones. As cats age and their lens becomes more rigid, their pupils may appear cloudy and their iris duller than before.

There are a few things to consider with your cat’s aging eyes.

  • Cataracts. Some cats have a predisposition to develop cataracts as they age and, just like humans, eye surgery is the best treatment, aside from prevention.
  • Melanocytoma. Typically benign, melanocytoma tumors aren’t painful to cats and show as small dark spots in the iris. However, they can become malignant and spread easily (iris melanoma,) so monitoring is essential.

Pay attention to their body

Just like us, as cats age, their body changes. It’s common for cats to lose muscle tone and mass, along with bone mass. Their skin may lose elasticity and become thinner, making them more susceptible to injuries and infections. These signs, along with the others on our list, can be situational. Inadequate nutrition and health conditions may cause similar symptoms.

The science behind cat aging

Just like with people, numerous factors go into how your cat ages. From genetics to lifestyle, here’s what goes into how quickly, and how well, your cat ages.

Genetics & environment

There are numerous factors that can impact your cat’s lifespan before they are ever born. Congenital conditions present at birth can help breeders and pet parents make informed decisions about the future.

Health conditions

Certain health conditions, like heart disease, can shorten your cat’s lifespan. Other heart conditions, like hypertrophic cardiomyopathy , can develop as cats age and impact their lifespan.

Another example is arthritis in cats. While arthritis itself won’t shorten your cat’s life, comorbidities, like obesity, can. It can also prevent cats from getting exercise or to the food and water bowl as often as they should, cutting them off from necessary nutrients.

Indoor vs outdoor cat lifestyle

There are many reasons as to why cats want to go outside. From exploring and hunting to socializing, cats just want to be, well, a cat. Unlike their bigger relatives though, outdoor cats are prey to many different predators found in both urban and rural areas. They can also fall victim to accidents, such as getting hit by a car or falling from too-high of a space, or more malicious intent.

All of these factors can reduce the chances of your outdoor cat making it to their golden years. There are a few ways to help mitigate this.

Go for walksCat harnesses are a great way to let your cat get some quality outdoor time without being on the menu for owls, coyotes, and even native wild cats.

Make indoors interesting — Many homeowners don’t think about how cats have an affinity for climbing. Utilize vertical space in your home by finding the best cat tree for your cat.

Build a catio —For cat owners who have a patio or deck, a catio is a great way to let your cat enjoy the outdoors without being in danger. It’s important to not leave your cat unattended though — cats can be determined and may try to make an escape.

Frequently asked questions

Does the conversion of cat years to human years vary based on the breed or size of the cat?

No, the conversion of cat years to human years does not vary based on the breed or size of the cat. The calculation is generally standard across all cats.

How is a cat’s age calculated in human years?

A cat’s age is calculated in human years through a method that counts the first two years of a cat’s life as 25 human years, and each additional cat year as 4 human years. This takes into consideration the rapid maturity of cats in their initial years and their slower aging later on.

Is there a formula to convert cat years into human years?

Yes, there is a formula to convert cat years into human years. The first year of a cat’s life is equivalent to around 15 human years, the second year brings the cat up to 24 human years, and each year thereafter is equal to about 4 human years.

Are there health milestones in a cat’s life that correspond to certain human years?

Yes, there are equivalent health milestones in a cat’s life that correspond to certain human years. For instance, a one-year-old cat is similar to a 15-year-old human in terms of physical maturity, and a two-year-old cat is on-par with a 24-year-old human. After that, each cat year roughly equates to about 4 human years.