How Long Do Cats Grow For?

How Long Do Cats Grow For?

One of the most exciting—and arguably most depressing—parts of owning a kitten is watching her grow and transition into a full-grown cat. But cats don’t suddenly stop growing once they reach the 12-month mark, weigh 12 pounds, or give birth to their first litter of kittens. So how long do cats grow for?

Cats usually grow rapidly for their first 9-12 months and then continue to grow a bit more slowly until the 18-month mark. However, some cats don’t grow much larger than their size at six months, while breeds like Maine Coons may not be fully-grown until they’re nearing the age of five.

Learning about how long your cat will grow can help you plan out when it’s time to switch to adult food, know how much space she needs in your home to feel comfortable, and ensure she’s on a healthy growth track. To find out how long your cat will grow for, read on.

A Cat’s Growth By the Numbers

It’s safe to say that the bulk of your kitten’s growth will occur during her first 16 weeks. Throughout her first four months of life, your kitten will develop her senses (hearing and sight), begin to walk unassisted, learn how to use the litter box, wean from her mother, develop enjoyment in playtime, and begin eating cat food.

A newborn kitten weighs just ⅓ of a pound and can fit in the palm of your hand. Your kitten will nearly double in size by her second week, triple in size by the three-week mark, and sit at around 12 times her birth weight by the time she’s four months old (4+ pounds).

To put this rapid growth into perspective, take a look at the kitten growth chart below.

Age (In Weeks)Average Weight (In Pounds)
10.3 to 0.6
20.4 to 0.9
30.8 to 1.1
40.8 to 1.3
50.9 to 1.8
61.0 to 2.0
71.2 to 2.3
81.4 to 2.6
101.8 to 3.1
122.2 to 4.0

The 16-week mark usually signifies your kitten is entering into her adolescent years—she’s officially a teenager! This major milestone also comes with a gradual slowing of your kitty’s growth. And while your adorable kitten will still look like a kitten in your mind, she’s already nearing her full-grown adult size. By five months, your kitty will weigh about 5-6 pounds and gain another 1-2 pounds by the time she’s half a year old.

The growth process of kittens and cats is interesting, and it goes quickly! Watch the video below to learn about when cat’s officially reach “adulthood” and the developmental stages they’ll go through before becoming adults.

What Age Is a Cat Full-Grown?

Somewhere between six months and a year old, you’ll notice that your kitten—who was once growing noticeably taller (and longer) and gaining up to a pound a month—isn’t growing quite as quickly. By about nine months old, your kitten will be about ¾ of her adult size and weight. Nine months old also happens to be the age at which many kittens have already reached a state of sexual maturity, meaning your unspayed kitten may begin going into heat (or spray).

This slowed growth rate will continue until your kitten is a year to 18 months old (in normal circumstances). But the 12-month mark is when many veterinarians will classify your kitten as an “adult cat,” so it may be time to switch over to adult food if your kitten’s growth is either slowing or stopped by this point.

How Big Will Your Cat Grow?

Many believe that a kitten’s approximate adult weight is about twice what she weighs at 16 weeks. So if your four-month-old kitten weighs 5.3 pounds, she may level out to around 10.6 pounds once she reaches adulthood (12 months old, in most cases). However, your cat’s exact adult weight is more likely to be within 10% of this value. Of course, this doesn’t take into account your cat’s breed or genetic make-up.How Long Do Cats Grow For?

Many cat owners also make the mistake of thinking of confusing “growth” with “weight.” Your cat will reach her full length and height by the time she’s about 18 months old. But that doesn’t mean her weight will automatically begin leveling out—that depends on how you’re feeding her! By “adulthood,” your cat should weigh about ten pounds, but this isn’t a guarantee if you’re overfeeding your cat or not giving her enough exercise.

Do Cats Grow After 2 Years?

Most cats will be “full-grown” by the time they’re 18 months old, with many reaching this major milestone within six months to a year—such is the case with dwarf cats and munchkins. But just like some cats will reach a point of full maturity by the age of six months, some cats continue to grow well past the two-year point.

The following larger cat breeds grow for two years or longer:

  • Maine Coon: 3-5 years
  • Ragdoll: 4 years
  • Bengal: 2 years
  • Persian: 2 years
  • Siamese: 2 years

It’s worth noting that your cat’s full-grown adult size doesn’t only depend on her breed but also her diet, genetics, and whether she’s fixed. Your domestic short-hair may very well grow for over two years, and your Ragdoll can theoretically stop growing as soon as 12 months.

Let’s talk about how those few factors can impact your cat’s size later in life.


Young kittens have fast metabolisms and need far more nutrients and calories each day to keep up with this year-long period of rapid growth. A kitten not getting enough vitamin B6, potassium, pantothenic acid, folic acid, calcium, sodium, and magnesium in her diet is more likely to experience stunted growth and achieve a smaller adult size. Nutrient and calorie-dense kitten food is a must until your kitty reaches “adulthood” at 12 months to prolong this growth stage.


Your cat’s coat length, color, and eye color depend on that of her parents. Your cat will get 50% of her DNA from both mom and dad. Similarly, your cat’s full-grown size may mimic her parents’ size. If your cat’s parents were both small-framed and weighed 7-9 pounds, it’s likely your cat will follow that same pathway and complete growth by 12 months. A purebred Maine Coon may grow for five years up to 3.3-feet long and weigh 27 pounds, a variant in their genetic code.

Spayed or Neutered

It was once a wide-held belief that spaying or neutering a cat stunted its growth. Research shows that the opposite is true. The closing of your cat’s bone growth plates occurs later in neutered or spayed kitties, meaning your cat may continue to grow for longer and grow to be bigger than a non-fixed cat. The longer you wait to fix your cat, the fewer health benefits of fixing (aside from not being fertile), and the more likely your cat will stop growing sooner.


Cat growth is tricky because, like humans, there’s no “standard” size and timeline. Some cats will stop growing as soon as six months old, while larger breeds like the Maine Coon or Rag-doll may not reach full-size until they’re four or five years old.

Your cat’s diet, genetics, and whether she’s fixed will also play a role in your cat’s adult size and how long she continues to grow. Feed your kitty kitten food until she’s about a year old and get her spayed (or neutered, for the male cats) as soon as possible to nurture healthy growth.