Cat Tips

How Long Do Cats Grow and When Do They Stop Growing?

If you’re a pet parent to a new kitten, you’re in for a treat. Kittens are adorable and tons of fun, although they might get a bit overwhelming at times. Since they’re learning as they grow, they can be more playful and explore more than an adult cat.

There are also different challenges and steps that kittens go through as they age, and you’ll need to be prepared. Although cats can be pretty independent, kittens do need a certain amount of oversight and care that an adult won’t need.

If you’re new to raising kittens, there are a few things you’ll need to know about their development. At Spot Pet Insurance, we know that taking care of a new pet, especially a pet that’s starting to learn more about the world, can be challenging.

To help you with that, we’ve put together a rough timeline of kitten development so that you know what to expect. Although this timeline applies to most cats, larger breeds, like the Maine Coon, have longer developmental periods.

So, how long does it take for a cat to fully develop? When do they finish growing, and what can you expect as they grow?

When do kittens start growing?

For most kittens, development will start right when they’re born. Although they may not grow in size right away, they continue to develop. However, once a kitten gets a few good feeds in, they will begin to gain weight and grow bigger.

Kittens grow a lot faster than human babies, so you can’t really measure kitten milestones by human ones. Some kittens also might grow a bit slower than their littermates, so you might notice that some kittens aren’t hitting milestones at exactly the same time.

As long as your kitten is hitting milestones roughly around the same time, they should be fine. However, you may want to talk to your kitten’s vet if they are a late bloomer. A professional will be able to tell if there is a problem or not.

Similar to human babies, kittens will need multiple checkups and vaccinations throughout their first year of life.

There are roughly three different development stages that kittens go through before they become adolescents, which is basically a fancy word for a teenage cat. The first of these stages begins at birth, and the last stage ends around the time they turn six months old.

Birth to six weeks

Kittens are born fairly helpless. The most they can do on their own is scoot themselves to their mom to eat. Their mothers will help them stay clean and fed, and, after the first couple of weeks, they should start developing.

By three weeks, their mother might start potty training them since the kittens are more mobile. You may need to invest in a smaller litter box that the kittens will be able to climb into.

Most kittens will still be with the breeder or rescue at this age since they are very reliant on their mothers. However, if you are caring for kittens this young, you can hold them for very short periods of time, and they should always be in the view of their mothers.

At around four weeks, the baby teeth, also known as milk teeth, will come in, so most breeders will start weaning around this age.

Seven to 12 weeks

Around the time they are seven weeks, kittens should be fully weaned and eat cat food made especially for kittens. This time is usually when kittens are adopted. They can move up to bigger litter box accommodations, and they are learning how to socialize.

They are energetic, and now is a good time to train them to get used to a carrier or a harness if you want to use one. Your kitten will want to play, and they may start kneading or scratching, so a scratching post might be helpful.

They’ll find more ways to get into trouble since they’ll want to start exploring more.

Three to six months

This phase is the final stage before a cat becomes a teenager. At around three months, your kitten will start to lose their baby teeth, which means they might start nipping and chewing on things more.

There are toys made for kittens to gnaw on while they are teething, and it would be around this time that cats might need bigger toys to play with so that they can hone their skills.

Your kitten may also try to test your limits at around this age. So, be consistent when you’re teaching them what they can and cannot do.

The teenage phase: six to 12 months

Kittens become adolescents around the time that they are six months. Some would consider them to be fully-fledged teenagers at about 11 months. However, at six months, you should probably consider getting your cat spayed or neutered if you don’t want any more kittens.

They start the process of becoming sexually mature around four months, and they are done by the time they are nine months. Still, in order to avoid females going into heat or males marking their territory, it’s a good idea to have them spayed or neutered when they reach six months or a bit older.

Cats are also about a half to three-quarters of their adult size. They will look a bit gangly since their legs might be longer than suits their size, but they will grow into them.

At roughly nine months, your kitten should have lost all their milk teeth, and their adult teeth should have come in. They might try nipping people around this time, so you should discourage that.

You can start transitioning their kitten food to adult food when they are ten months old. The best way to do this is to gradually add a little bit of adult food to their kitten food at a time until the kitten food has been replaced.

By the time they’re 12 months, kittens will have reached the end of their teenage phase, but some breeds might still have a playful and energetic nature, while others might calm down a bit.

When do kittens become adults?

When a kitten is one year old, most people will agree that the kitten is now an adult cat. They will have reached maturity, although it may take some breeds longer to become fully adult.

Large breeds, like the Maine Coon, take longer to develop. Maine Coon cats don’t reach full maturity till they’re around two or four years. American bobtail cats don’t become fully mature till they are at least two years old. You may also be interested in Japanese Bobtail

Savannah cats are another breed that takes a while to become adults. Most experts will agree that they are fully mature around two to three years.

If you want to know when your kitten is supposed to reach adulthood, it might be a good idea to look into the breed of cat that you care for. You could also talk to a vet during your cat’s wellness visits.

From tiny kitten to adult cat

Adopting a kitten can be a huge responsibility and might be a little overwhelming, especially if this is your first time raising a kitten. By learning what to expect and how to handle it, raising a kitten will be a lot easier.

Kittens develop rather quickly, so there will be a lot of challenges for your kitty one after another, especially when they start teething. However, with a little time and effort, you can make your kitty’s first year a great one.

It’s also important to keep track of important periods, like when it’s time to take your kitty to get spayed or neutered so that you don’t have any territory marking or more kittens. With this quick guide, hopefully, you can have a better understanding of the phases your kitten will go through and what you need to help them with.

If you’re looking for more tips about cats and their habits, you can check out our blog.


  • Kitten Development From 6 Months to 1 Year | The Spruce Pets

  • Retained Deciduous Teeth Baby Teeth in Cats | VCA Animal Hospital

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