Cat Years Calculator & Chart: Your Cat’s Age in Human Years

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By Pet Expert Team
Updated: 5/15/20242-4 minutes
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According to popular legend, one human year is the equivalent of seven "cat years," but in reality, a one-year-old cat is much more mature than a seven-year-old child. Learn all about your cat’s lifespan and how old they are in human years in this guide.

What is a Cat Year?

Differing with each age, cat years are equivalent to many human years. We can easily work out cat years to human years with simple math. Knowing this allows us to understand a cat’s maturity and their needs dependent on age – like their food intake, potential cat illness, and activity levels.

How Old is My Cat in Human Years?

The first two years of a cat’s life are roughly equal to the first 25 of a human. After this, add four "cat years" for every human year e.g., if your cat is six years old, its equivalent cat age in human years will be around 41.

It’s important to note that there’s no reliable scientific way to calculate the relationship between human and cat years, but this is a good rough outline to guide us.

How Many Cat Years Are in a Human Year?

The first year of your cat’s life is considered the equivalent of 15 human years. The second year adds nine more human years, so 2 cat years are approximately 24 human years. After this, each additional human year is four "cat years" i.e., age 3 will be 28 human years. 

Cat Age Chart

Comparing human years to cat years is simple!  Although other factors, such as breed, might also influence how old your cat is in human years, roughly, five year old cat would be 36 in human years and a 15 year old cat would be 76 in human years. 

See the differences between cat years and human years with our cat age chart below.

Cat Age Human Age Cat Age Human Age
1 years15 years 10 years56 years
2 years24 years 11 years60 years
3 years28 years 12 years64 years
4 years32 years 13 years68 years
5 years36 years 14 years72 years
6 years40 years 15 years76 years
7 years44 years 16 years80 years
8 years48 years 17 years84 years
9 years52 years 18+ years88 years

What is the Average Cat’s Life Expectancy?

The true answer is that it depends, but indoor cats usually live longer than outdoor cats. The average indoor cat lifespan is 16 to 18 years and some even reach (or pass) the venerable age of 20. Most outdoor cats have an average lifespan of 13-14 years.

Life expectancy in cats also varies depending on the breed, as some cat breeds will naturally live longer than others. For example, Siamese and Manx breeds are said to live the longest, so they could reach a ripe age in human years!

Did you know? According to some sources, the world’s oldest cat lived to be 34? That’s 153 in human years! Read more fascinating cat facts here.

Cats’ life expectancies have increased dramatically in the last few decades. Although it’s never enough, we’re spending more and more time together with our feline friends and that can only be a great thing.

How Do Cats Age in Human Years?

Cats age very quickly in their first two years of life, after which the process slows down and becomes more gradual. The way in which a cat’s age is determined is based off its physical and behavioral changes. These stages are then matched to those of a human life cycle. 

Why is it Important to Know a Cat’s Age in Human Years?

It is important to know the life stage that they are at so that you can prepare yourself for any age-related health issues that may occur. Knowing when your cat has transitioned into their mature, senior cat years will help you give them the best care possible. 

How Can I Tell My Cat’s Age?

To find out how old your cat is, it’s best to take them to a vet. But you can still look for tell-tale signs of a cat’s age and health. You (or your vet) can look for these signs in their teeth, fur, eyes, muscles and bones. We have more information on this below.


Teeth can’t pinpoint the exact date for your feline friend’s birthday party, but they are still a great indicator of a cat’s age. The milestones are:

  • A kitten’s first teeth appear between two to four weeks.
  • Their permanent white teeth come in at around four months.
  • Yellow stains (aka tartar) on a few teeth can mean your cat might be between one or two years old.
  • If the stains appear on all teeth, the cat is likely at least three to five years old.
  • Missing teeth are usually a sign that your cat is a respectable senior, between 10 to 15 years of age.
  • But keep in mind that some cats can just have worse teeth than others regardless of their age.


If your cat’s teeth are not always the reliable indicator you hoped for, eyes can give you a useful clue regarding your cat’s age. The difference between a smooth iris and a crackly looking one can be the difference between a young cat and a senior one.

After 12 years of age, cat’s eyes usually start showing cloudiness. And if you notice tearing and eye discharge, you likely have a senior cat on your hands.

Muscles and Bones

Age can hide behind appearances so pay attention to features that can complete your cat’s age picture. As in humans, a higher activity level gives your cat muscle definition. Playing, jumping and running are a young cat’s game. So, if you notice that your cat tends to lose muscle mass or they don't like to move around too much, this might be a sign of aging. Older cats may be bonier, have extra skin hanging or protruding shoulder blades. Read our cat body condition guide for more tips.


A cat’s fur changes with age. Fine, soft fur is usually reserved for young cats only. Older cats tend to have a thicker, coarser fur with patches of grey hair.

Now you know all about cat lifespans and how their age converts in human years! For more expert tips on a cats life, explore our other cat behavior articles.

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