How cat years work

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Alison Mcdermott


How old is my cat in human years? This is a question many of my clients asked during my apprenticeship at a local pet hospital. So in this post, we’ll show you how to calculate their age, include a handy chart that shows their age in human years , explore their life stages and factors that determine how they age. 

Chart of cat years converted to human years

Let’s get right to the answer with an age chart. 

cat years human years
1 15
2 24
3 28
4 32
5 36
6 40
7 44
8 48
9 52
10 56
11 60
12 64
13 68
14 72
15 76
16 80
17 84
18 88
19 92

How to calculate their age

Understanding how cat years work is actually quite simple. 

  • First cat year = 15 human years
  • Second cat year = 24 human years
  • Years after =  add 4 human years for each year

When a cat is born, they go through a rapid growth phase, similar to human infants. This is why the first 2 years of a cat’s life are calculated differently than the later years.

In the first year of a cat’s life, they undergo significant physical and behavioral changes. By the time they reach their first birthday, they are roughly equivalent to a 15-year-old human in terms of development.

The second year of a cat’s life is also characterized by continued growth and maturation. By the end of their second year, they are approximately equivalent to a 24-year-old human.

After the initial two years, the rate of aging slows down, and each additional cat year is roughly equivalent to 4 human years. This means that a three-year-old cat would be approximately 28 years old in human years,  a four-year-old would be around 32 years old and so on.

This is a general guideline but factors like breed, genetics, and overall health influence how a cat ages as we will see later.

Life stages of cats

  • Kittenhood (0-6 months): Rapid growth, high energy, and playful behavior characterize this stage.
  • Junior (7 months – 2 years): Continued growth, exploration, and sometimes a bit of teenage rebellion!
  • Prime (3-6 years): Adult cats are at their physical peak, maintaining a good balance between activity and relaxation.
  • Mature (7-10 years): A cat is considered middle-aged at this point, and you might start noticing subtle signs of aging.
  • Senior (11-14 years): Cats in their golden years require a bit more attention to health and comfort.
  • Geriatric (15+ years): Extra care is needed for cats in their twilight years, including regular vet check-ups and adjustments to their environment.

Factors that affect aging in cats

  • Breed: Different cat breeds can have varying lifespans and aging rates. For example, smaller breeds often live longer than larger ones. 
  • Genetics: Just like in humans, genetics play a significant role in a cat’s aging process.
  • Health: A cat’s overall health, including diet, exercise, and preventative care, can greatly influence how they age.

Thank you for reading and see you in our next post!

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