If you’ve ever looked at your tiny kitten and wondered how long they’ll stay that small, you’re not alone. One of the most common questions new cat owners ask is: when do cats stop growing?

The short answer is that most cats reach their full size between 12 and 18 months old. But like most things in life, it’s not quite that simple. Breed, genetics, diet, and overall health all play a role in how big your cat will get and how fast they’ll grow.

Let’s break it down in a simple, practical way.

When Do Cats Stop Growing?

Most domestic cats stop growing in height and length around 12 months of age. However, some cats continue to fill out and gain muscle until they are about 18 months old.

Large breeds can take even longer. For example, the Maine Coon may continue growing until they are 3 to 4 years old.

So if your cat still looks a bit lanky at one year old, that’s completely normal.

Kitten Growth Stages Explained

Understanding your cat’s growth stages helps you know what to expect.

1. Newborn to 2 Weeks

Kittens are tiny and completely dependent on their mother. Growth during this stage is fast. They typically double their birth weight in the first week.

2. 2 to 8 Weeks

This is a rapid growth phase. Kittens start walking, playing, and transitioning to solid food. Their bodies grow quickly in both length and weight.

3. 2 to 6 Months

Your kitten now looks like a smaller version of an adult cat. Growth is still steady, especially in bones and muscles.

4. 6 to 12 Months

Growth starts to slow down. Most cats reach their adult height and length by the end of this period.

5. 12 to 18 Months

While they may not get taller, many cats continue filling out. Their chest broadens and muscle definition improves.

Do All Cats Grow at the Same Rate?

No, and that’s important to remember.

Several factors influence how long cats grow:

Breed

Some breeds are naturally larger and take longer to mature. Besides the Maine Coon, breeds like the Ragdoll also grow more slowly and can take up to 3 years to fully mature.

Smaller breeds often reach their full size closer to 12 months.

Genetics

If your cat’s parents were large, your cat is more likely to be large too.

Nutrition

A high-quality, balanced kitten diet plays a major role in healthy growth. Poor nutrition can slow development, while overfeeding can lead to unhealthy weight gain.

Spaying or Neutering

Some studies suggest that early spaying or neutering may slightly affect growth plates, sometimes resulting in slightly taller cats. However, the difference is usually minimal.

When Do Cats Stop Growing in Weight?

Even after they stop getting taller, cats may still gain weight as they develop muscle mass. Most cats reach their adult weight by 12 to 18 months, but large breeds may take longer.

It’s important to distinguish between healthy weight gain and excess fat. If your cat seems to be gaining too much weight after their first year, a quick chat with your vet can help you adjust their diet.

Signs Your Cat Has Reached Full Size

You might notice:

• No significant increase in height or length

• Slower weight gain

• A more muscular, filled-out body

• Stable appetite and energy levels

If your cat’s growth has clearly slowed and they look proportionate, they’re likely at or near their full size.

What If My Cat Seems Too Small?

If your cat is smaller than average, don’t panic. Some cats are naturally petite.

However, you should consult a vet if you notice:

• Poor appetite

• Lethargy

• Noticeable weight loss

• Delayed development compared to littermates

Early intervention makes a big difference if there’s an underlying issue.

Final Thoughts

So, when do cats stop growing? For most cats, the main growth phase ends around 12 months, with full maturity by 18 months. Larger breeds like the Maine Coon may continue growing for several years.

Every cat grows at their own pace. Focus on providing proper nutrition, regular vet checkups, and lots of love. Before you know it, that tiny kitten will be a fully grown companion curled up on your couch.