How Big Will My Kitten Get? Check This Guide

As you know, cats come in different sizes. You can have a tiny Singapura or a massive Maine Coon. However, if you adopted a young kitty, you’re probably wondering: how big will my kitten get? The answer to this is more complicated than merely measuring alone. We have to factor in the breed, overall health, and the age of the kitten to know how big its adult size would be.

Kitten size by age

By the time a kitten was born, it would be tiny. At the first week of its life, it would only weigh 3 to 5 ounces.

how big will my kitten get

As weeks pass by, the kitten will keep getting bigger and stronger. A tabby kitten will weigh 15 ounces by the time it reaches three weeks old.

Kitten size by age

To give you a better idea, here’s the average weight of a kitten as it grows old:

  • 0 to 3 months: about 9 to 12 pounds
  • 3 to 6 months: about 12.5 to 16 pounds
  • 6 to 9 months: about 16.5 to 19.5 pounds
  • 9 to 12 months: about 20 to 23 pounds
  • 18 months: about 23.5 to 26 pounds
  • 24 months: about 26.5 to 28 pounds

Most cats will achieve its full size by the time it reaches a year old. However, more giant breeds will take up to 18 months. If you’re wondering how big your kitten will get, the chart above will give you an idea. please read here when does a kitten become cat

Try to look for the kittens’ parents to have an idea of how big it will get. However, if the kitten is a stray, it would not be easy to guess, so you have to wait until the kitty becomes bigger and older.

Factors that affect the cat’s size

A lot of factors are at play on how big your kitten will get. The following are some of the most common aspects that will affect a cat’s size:

  • Breed

If there’s one factor that will have a direct impact on how big your kitten will be, it’s the breed. Genetics is undeniable, and it will always show on your kitten’s appearance. If your kitten has a Ragdoll or Maine Coon parent, it’s likely to be bigger than usual even if the other parent is average in size.

  • Diet

The diet of your kitten will also affect how big it will get. Even if it’s a big breed, poor feeding can cause stunting among kittens.

It may appear thin and short, even after reaching a year old. If you want to know the exact size of your kitten, make sure that you provide it with nutritious meals.

cat diet

The diet of the mother cat will also affect how big its kitten will be. Poorly fed mother cats will produce sickly and stunted kittens.

  • Spaying/neutering

Contrary to myths, cats don’t get fat and big when they are desexed. In fact, neutered or spayed kittens tend to be slimmer because of the hormonal shifts. Still, each cat is different, so desexing may not really affect its full size later. Nevertheless, desexing a kitten has its perks, especially if you don’t want to have more kitties in the future.

Biggest and smallest cats

Are you wondering what the biggest and smallest cats are? Since the breed is a determinant of how big a kitten will be, I think it’s important that you have an idea about its varying sizes. Below are the smallest and biggest in the domesticated feline world with their adult size:

big and small cats

Smallest cats:

  • Singapura – weighs 8 pounds
  • Devon Rex – weighs 9 pounds
  • Cornish Rex – weighs 9 pounds
  • American Curl – weighs 5 to 10 pounds
  • Munchkin – weighs 5 to 9 pounds
  • Sphynx – weighs 6 to 12 pounds


Largest cats:

  • Maine Coon – 8 to 25 pounds
  • Norwegian Forest Cat – 10 to 20 pounds
  • Ragdoll – weighs 8 to 15 pounds
  • Siamese – 8 to 12 pounds
  • British Shorthair – 7 to 17 pounds
  • Bengal – 10 to 15 pounds

Are indoor cats bigger than outdoor cats?

There’s no substantial difference in how big an indoor kitten will be as compared to an outdoor one. However, most outdoor cats are lighter because they have the freedom to run around. In contrast, indoor kittens can have limited activities. If you don’t watch out over its diet, it can get big and obese. It’s unhealthy and must be addressed right away. Please read here: How Fast Can A Cat Run

What is the average height of a cat?

What is the average height of a cat

Most cats will have an average height of 23 to 25 cm. Kittens will grow big fast over the first few months of its life.

The growth is usually concentrated on the first six months as your kitty packs on more weight and height.

By their first year, your cat will achieve its full size. Still, its breed is at play here, which is why cat sizes may vary.

Can you tell how big a kitten will get by its tail?

I was surprised that a lot of pet owners ask this question. The tail isn’t really an indicator because some cat breeds are tailless. Also, a kitten’s tail will grow simultaneously with its body.

What you need to check is the length of the back legs. Tall back legs usually indicate that your kitten will be a big cat. By four months, your kitten should have gained substantial weight that will progress as it inches closer to one year.

When do cats stop growing?

Cats grow at a fast pace during its first months. You’ll see a massive growth in the first four months, which will slow down once your kitten reaches six months old.

Most cats will stop growing bigger by the age of 12 months, while others will get bulkier for another six months.

When do cats stop growing

Usually, neutering and spaying will not affect when your kitten stops getting bigger. Still, some cats may react differently to the hormonal change, especially if the desexing is done at a very early age.

How big does a kitten have to be for spaying?

Spaying or neutering isn’t decided based on the cat’s size. It should always be about how old your kitten is. Most of the time, kitties can be fixed once it reaches eight weeks of age or about two pounds of weight.

Some vets will advise waiting for a little longer until the kittens’ hormones stabilize. But as much as possible, you should get your kitten spayed within the first six months of is its life. This will prevent their sexual overdrive from getting the best of them.


How big will my kitten get? It depends on its breed, age, diet, and other factors. No matter how big your kitten is, you should always take good care of it. If you notice any problem as the kitten grows bigger, you shouldn’t hesitate to talk to an expert.

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