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When Do Cats Reach Full Size? (Cats Stop Growing!)


Your fun and energetic playmate grow into their natural adult size in what seems like a flash, things can move pretty fast if you don't pay attention. But just when do cats reach full size?

Well, much like humans, every cat is different, and there are variables to consider. Having your pet neutered or spayed can influence just how fast or slow your cat takes to reach full size.

Generally When Do Cats Reach Full Size?

To be quite vague, a lot of people believe a feline becomes an adult around the age of 12 months. This is a guideline though, as your cat might not be quite done growing by this time, indeed it might already be fully grown at this point.

A kitten will grow rapidly in weight and size until anywhere between 9-12 month, for another 6 months after this they will likely still grow, although not in such a fast way.


A kitten will grow rapidly in weight and size until anywhere between 9-12 month

This is also the age your cat will need added stimulation if they are indoor pets. Try give them paces to climb, toys to play with and explore.

Around this time you will also notice your cat becoming territorial. If you have more than one cat in the house you might want to be a little selective as to where you place feeding and water bowls as well as litter boxes and places for them to relax. 

You might have a household where everyone gets on just fine in which case there will be no need to change anything.

When Do Cats Reach Full Size? - The 4 Phases

This is often credited with the development of your cat until they reach adulthood.

The transformation from kitten to Cat will generally take up the first 12 months of your felines life, with the stages in between known as the following:

  • Birth > 7 Weeks - Mostly spent with their mother, growing and getting stronger
  • 7 > 12 Weeks - When you can take your kitten home and when they start to become playful and curious
  • 3 > 6 Months - The starting of behavioural changes as well as noticeable physical growth
  • 6 > 12 Months - when they go from kitten to cat.

Independance - What Influence When Cats Reach Full Size

You might notice that your furry friend is acting differently and wishes to stay close around the formative months before they begin the process of reaching adulthood. So look for a change in behaviour around when they are 6 months old.


All the hormonal changes that are starting to go on in cats' body make them act differently

This is because of all the hormonal changes that are starting to go on in their body. This will continue until they are a fully fledged adult and at this point they are likely to be a lot calmer as they reach adulthood.

It is important for you to handle and play with your cat throughout this time to ensure they are used to being social with humans. This is also a good way of making sure you are in tune with their changes in personality as they reach full size.

Spay or Neutered Cats


Catmight be fully grown in terms of size, but personality wise might not develop at the same pace

These cats can take a little longer to mature and they will be playful and almost a little clingy into adulthood. They might be fully grown in terms of size, but personality wise might not develop at the same pace as a cat that has not been spayed or neutered.

When your cat is developing, to set boundaries use a gentle approach. Using a spray bottle should be enough to help. Remember never to strike your pet or be overly strict. Sometimes they are listening to your instructions, but not necessarily acknowledging them.


If you are wondering when do cats reach full size because you are considering switching their food from a kittens to a food more suitable for a cat then around the age of 1 year old is a good guideline. 

Their health and general requirements will change around this time so to give them the best chance of getting everything they need, give them a quality food that is relevant for their age and size.


Change food every period to give cats a quality food that is relevant for their age and size

The best way of making the transition is by mixing a little bit with their current food before adding more of the adult food over the course of the next week until their whole meal is made up of adult feed.


Some breeds will continue to grow beyond the usual time frame. Some of the larger breeds, typically like Maine Coon and Persian cats will keep growing, even until the age of 4!


Remember like we said all cats develop at different paces, the above is just a guideline as to what you can expect around the time of when most cats reach full size.

There is no need to worry if your cat is taking a little longer, or if they have stopped growing before the time you might expect.

If you ever have any real concerns about their development you can always consult your vet.

About the Author Cindy Grant

A pet lover from Boston, USA who is extremely passionate about all cute little pets, especially puppies, kittens and birds. I created NolongerWild as a community where all pet lovers around the world can meet and share their passion with each other.

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