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When Do Cats Stop Growing? When Do They Reach Full Size?

When Do Cats Stop Growing? When Do They Reach Full Size?

That is probably the first question that comes into the minds of new cat parents. And I know what you’re thinking, your little fluffy cat keeps growing and you want to know what to expect.

Your cat will hit many milestones that will mean that he or she is becoming an adult, but there’s no specific age to where he or she will stop maturing. However, there are general stages where most cats will reach adulthood and then stop growing, usually by the end of the first year.

Even though many kittens stop growing when hitting the 12 months mark, not all cats are finished growing at this age. However, if they continue to grow, we must be aware that it will be a much lower rate than before. We can expect our cats to be close to their full adult size generally between 12 to 18 months.

Do Cats Keep Growing As They Get Older?

We see children continue to grow as they age and when turning 18, they are usually considered to be adults; and we expect the same from our feline friends.

There is one main goal after a perfect friend comes into this world – and it is to GROW! And they do that pretty rapidly. But what should you expect?

weigh a cat

In a matter of weeks, cats usually grow eight times their size:

  • Under 7 days: they weigh less than 4 ounces.
  • 7 to 10 days: they weigh from 4 to 6 ounces.
  • 10 to 14 days: they weigh from 6 to 8 ounces.
  • 14 to 21 days: they weigh from 8 to 12 ounces.
  • 4 to 5 weeks: they weigh from 12 ounces to 1 pound.
  • 6 to 7 weeks: they weigh from 1 pound to 1 pound and 8 ounces.
  • 2 months: they weigh from 1 and a half pounds to 2 pounds.
  • 3 months: they weigh from 3 pounds to 5 and a half pounds.
  • 4 months: they weigh from 5 and a half pounds to 7 and a half pounds.
  • 6 -12 months: they go from 8 pounds to 15 pounds, just reaching adulthood.
  • 2 years or more: they are behaviorally and socially mature.

At What Age Are They Fully Grown?

By the end of the first year – between 9 and 12 months – is when their growth slows down and most cats can be considered adults; reaching their full adult weight and size. But there may be some cats that will take up to 2 years to fully grow.

Indoor Cats Or Outdoor Cats, Which Are Bigger?

Despite their different circumstances, there’s not a great difference in their growth. Although, you should expect the outdoor cat to be lighter than the indoor cat, just because the latter one is presumably fed every day – and maybe even overfed – by his or her human.

How Big Can A Cat Get?

This will depend on many factors, a great part of them come from the cat’s upbringing but most have to do with breed. Now, regardless of the cat’s breed, the fastest growth will be seen during the very first months of age.

Every cat is different and probably, the best indicator of how big your cat can get is to look at your kitten’s parents – if this an option, considering that a lot of cats are adopted – however, gender can also be a factor. The tendency is that male cats are usually bigger than female cats, but it’s not a huge difference.

The average-sized adult cat should weigh about twice as much as it did at the 4 or 5 months mark. What can be done is to weigh your cat at 16 weeks (use a food scale or something else that is also small, in order to get a more accurate weight measurement), and multiply it by 2. Anything within about 10% of this number, either up or down, is a pretty good estimate for their final size. You can use this simple formula to get a loose idea of what that estimate might be.

Kitten weight at 16 months * 2 = Adult Cat Weight

Some big breeds like the Ragdoll and the Maine Coon will continue to grow even after their first 12 months, and they will continue to get bigger up to the 18th month.

cats of all sizes

Small Cat Breed

There are so many cat breeds, but here are some of the small ones and how big they can get.


They are small cats and can be very friendly. Their weight goes between 6 and 9 pounds.


Even though they can easily trick you with their fluff, these tiny felines can weigh between 5 to 9 pounds. It is considered a dwarf cat breed.

Cornish Rex

It is a small cat recognized for its beautiful and elegant appearance. Females can weigh in between 5 and 8 pounds, while males are usually between 8 and 10 pounds.

Devon Rex

Slightly smaller than the Cornish Rex, the Devon Rex weighs in from 5 to 7 pounds if female and between 7 to 9 pounds if male.


It’s officially the smallest cat breed in the world. With an average of 5 pounds, females can weigh as low as 4 pounds and males as low as 6 pounds.

Large Cat Breed

Larger breeds can take longer to grow. Here are some of the largest cats out there and what to expect from them in terms of size.

Maine Coon

These are the largest domestic breed, they can weigh between 10 to 25 pounds – or more – depending on their height and if it is a male or female.


They are originally from Mesopotamia (modern-day Iran), in size, these are considered medium to large. Males usually weigh from 9 to 14 pounds while females from 7 to 11 pounds.


These cats are compact and very heavy to our surprise. They tend to weigh from 8 to 12 pounds.

Egyptian Mau

Loved by the Egyptians and we understand why. Males and females tend to weigh from 8 to 12 pounds.

Cat Growth… In The Guinness Book Of World Records

Our little furry animals also break records depending on their size when they get to grow… or not. A munchkin cat named Lilieput holds the record for the shortest cat, as in the Guinness Book of World Records. While a Maine Coon cat named Stewie held the record for the longest cat at 48.5 inches stretched out, as listed in the Guinness Book of World Records.

kittens in yarn basket

How Can You Help Your Cat Grow Regardless Of Their Size

It takes a lot of work into your cat’s growth and development. Here are some extra tips to ensure health for your kitten.

Immunizations: Visit the veterinarian on their scheduled visits to ensure your cat gets all the necessary vaccinations. Very young kittens will require a series of immunizations, rather than just one single vaccine once a year or every three years. Boosters are usually administered every few weeks between the ages of 2 and 3 months.

Feed your cat with high-quality food: Many times, cat food is specially formulated with extra protein, vitamins, and minerals that help kittens grow. Feeding your kitten adult food ay not provide the necessary nutrients to sustain healthy development and all that cat energy! In order to help sustain all-day energy, a good idea may be to allow your kitten to feed by grazing throughout the day instead of only in specific mealtimes. Dr. Jim Carlson, owner of the Riverside Animal Clinic says “from 6 months to a year, an owner can feed three times a day”.

Weigh cats as they age: Weighing your cat once a month is usually a good idea. This way, you can monitor his or her growth more easily and ensure he or she is not gaining or losing weight too rapidly over time. If anything seems abnormal, call your veterinarian for advice.

Get the habit of grooming early: It can be challenging to teach your cat to be comfortable having nails trimmed and his or her teeth brushed later in life. Therefore, it’s much easier to establish these routines when your cat is young so you will have a better time taking care of his or her overall hygiene and grooming.

Supervision: Many cats are extremely curious and may find themselves in very sticky situations, whether it’s chewing on wires or tangling in cords and strings. Make sure you’re keeping the cat away from any potentially dangerous areas and if possible “kitten-proof” your home, in order to prevent injury.

What Else To Take Into Consideration

We also have to look into the lifestyle of our cats when considering their growth. A cat who has a sedentary lifestyle and a poor diet, or maybe has access to a lot of food during the day, will probably continue to store fat which is not necessarily growth. Our chubby kitty-cat might look cute, but a cat with obesity is actually an unhealthy condition for any pet.

And always, providing a healthy diet for your cat, as well as giving him or her a freshwater source and making it easy for him or her with an environment with plenty of space to exercise – with hiding holes to explore and places to climb – will help him or her to grow big and strong and happy as they could be!

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