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Cat eating, sitting, playing with yarn, and lying down, with a bird nearby.
Pet Blog

When Do Cats Stop Growing?

Are you watching in awe as your kitten grows like a fuzzy little beanstalk? They’ll slow down eventually—and there are several markers you can use to know when your kitten will stop growing.

Timeline for a Growing Kitten

Just like every human, every cat is different. Still, most common house cats reach big milestones around the same time on their journey to adulthood.

  • 3 to 6 months: Kittens’ baby teeth start to fall out and are replaced by adult teeth! (This is your chance to add some fangs to their kitty scrapbook.)
  • 4 to 9 months: Kittens reach sexual maturity. Females can be spayed quite young, but vets recommend waiting to neuter male kittens until they’re 5-6 months old.
  • 6 months: Rapid growth starts to slow down. Your kitten is still growing, but they won’t look like they’ve doubled in size overnight anymore!
  • 9 to 12 months: At this point, your cat should be about 95% of its adult size—this is their teenage phase where they’re almost fully grown but still learning the ropes.
  • 18 months: This is when most cats reach their full size of around 12-14 pounds. You can finally knit that cat sweater you had been waiting on.
  • 2 years: Cats reach adulthood. Based on how goofy some adult cats still act, “reaching maturity” might be a misnomer, but 2 years of age is the point where they’re socially and behaviorally mature.

These milestones can also help you estimate your kitten’s age if you’re not quite sure how old they are. Strays aren’t usually too fussy about marking their birthdays down on the calendar, so we take whatever help we can get.

Male vs. Female Cats

Male cats are typically a little bit larger than females—about 10 to 15% larger, according to vets. That means male cats will often be closer to the 14 pound mark and may take a little longer to grow, while many female cats will stay smaller and may reach their full size sooner. Of course, these rules aren’t hard and fast—we definitely know some feline gals who hit like a tank when they come in for a head rub.

Does a Cat’s Breed Make a Difference?

Things might look a little different for small or large breeds. Smaller breeds like Siamese and Sphynx cats typically have a lower body weight than your average house cat and can reach their full weight sooner. Larger breeds like a Maine Coon which can weigh over 25 pounds will continue to grow for longer than the average cat. It can take them 2 to 3 years to reach their full size.

Check with your veterinarian about what the average adult breed size is for your cat and if they might have an adjusted growth timeline. This will help you keep track of when your cat reaches adulthood—and when you should switch from kitten food to adult food.

When to Transition to Adult Cat Food

Most kittens get to enjoy a full buffet experience when they’re young! They have extremely high energy requirements until 6 months of age because their growth rate is so mind-bogglingly fast. That means most kittens will benefit from free-feeding on as much kitten food as their little hearts desire! From 6 months to a year old, vets recommend providing three meals a day. You know the drill—breakfast, lunch, and dinner.

At around 10 to 12 months old, it’s time to start thinking about introducing your cat to adult food. That estimate might vary a little bit if you have a large breed that’s still growing or a cat who’s done growing and is starting to get a little chonky chowing down on high calorie kitten food. Check with your vet to see if they agree it’s time.

When you’re ready to make the swap, make sure to transition gradually. Cats don’t appreciate having their favorite food taken away cold turkey (and neither do we), so it helps to start adding in a little bit of adult food at a time as you reduce their beloved kitten food. You can find more advice on how to make a smooth transition here—and before long your big kid cat will have a new favorite dinner.

We all know the feeling of wishing our babies could stay tiny and adorable forever (and who could forget the world’s tiniest toe beans?), but there’s something special about watching your cat grow from a wobbly little kitten into a fully grown cat with a big personality all their own.