Kittens grow so much during their first year of life. They’re born without the ability to do almost anything for themselves, and by four months old they can have kittens of their own!
Whether you’ve found a kitten or your cat is expecting, it’s important to know what to expect as the weeks go by. This can help you provide proper care and avoid making mistakes with the kittens at this fragile age.
In this article, we’ll talk about the development milestones in a kitten’s life, how much they weigh at each stage, and how to care for them. We’ve also included a complete kitten growth chart!
Table of Contents:
Week 1: Newborn Kittens
Newborn kittens can’t see or hear. They stay very close to their mother, either sleeping or eating. They depend on her for warmth, sustenance, and even going potty.
You might notice the umbilical cord still attached to the kittens.
Even at this age, they can communicate with their mom through crying and purring.
Newborn kittens typically weigh just 50-150 grams and grow to 150-250 grams in their first week.
Week 2: Opening Eyes and Ears
Kittens’ eyes may start opening as soon as two days old, but most times their eyes won’t open fully until the age of 1-2 weeks. At this age, the eyes are blue, but this will change for many cats as they age.
Don’t panic if one kittens’ eyes are slower to open than their siblings or if one eye opens before the other. These things are normal, and every kitten develops at their own pace. You’ll know it’s time to see a veterinarian if your kitten’s eyes still aren’t open after two weeks or if they have crust around their eyes.
Kittens’ ears also slowly unfold over time, and should be opened by their second week of life. However, the kittens still won’t see or hear as clearly as a grown cat.
Don’t allow bright lights and loud noises around the kittens, as their eyes and ears are still fragile.
In addition to their gained senses of sight and sound, kittens will gain a bit of mobility. They’ll move on wobbly legs, and still won’t stray far from mom.
After the first week, kittens no longer have umbilical cord attached. They typically weigh 250-350 grams by the end of their second week.
Week 3: Gaining Mobility
Week three is when kittens really start to move and gain a bit of independence! This is an exciting time in a kitten’s life.
They’ll start off walking on shaky legs, and as the week goes on they’ll gain more balance, strength, and confidence.
You can also sex the kittens at this age, which will be important information later on as they develop. For now, the boys and girls can stay together and are too young to mate.
Kittens’ teeth start growing at this age and they can be introduced to wet food, though they won’t wean from their mother’s milk for at least a couple more weeks.
Kittens also gain the ability to potty on their own during week three, so they should be provided a litterbox to do their business in. Any container with a waterproof bottom and shallow sides will do, but regular litter boxes for adult cats are typically too difficult for kittens to climb into at this age.
After all, they’re still tiny–most will weigh between 350-450 grams.
Week 4: Learning to Play
Week four is when kittens get confident enough on their feet to play! They’ll roughhouse with their siblings, initiate play with mama cat, and can even bat around toys.
This is when the humans in the family should get involved with socializing the kittens, if they haven’t already. Getting them used to humans at this age will set them up for success later in life.
Of course, you don’t want to remove the kittens from their mother and siblings. They should be spending most of their time with their kitty family. Four-week-old kittens still spend most of their days sleeping, which is incredibly important to their development, and they need to nurse from their mother regularly as well.
At four weeks, most kittens weigh 450-550 grams.
Week 5: Weaning
During week five, kittens can slowly be weaned onto wet kitten food. It’s important that they get a high-quality diet that provides the right nutrients for their age.
Once the kittens are fully weaned, they’ll need round-the-clock access to both food and water. It’s important that they get enough food at this age to sustain their rapid growth!
This is also the time that fosters begin preparing to release mama cat if she is feral. Keeping her indoors is stressful, and the kittens will no longer need her once they’re fully weaned.
However, the kittens should not go to new homes at this stage–they’re still heavily dependent on their siblings for socialization and to learn how to be cats!
At five weeks, most kittens weigh around 550-650 grams.
Weeks 6-8: Socialization
Now that the kittens are moving about and either mostly or fully weaned from mama cat, it’s a prime time to socialize them. They should be learning how to play appropriately without biting humans, how to behave while having their nails trimmed and coats groomed, and more.
Perhaps even more importantly, kittens at this age are still learning from their littermates. They don’t technically need their mother anymore, but they’ll still suffer if removed from their siblings.
Littermates teach one another bite inhibition (not biting too hard during play), manners, and so much more (see also ‘Cat Love Bites‘). They’re basically still learning how to be cats!
Of course, socialization is a long and complex process–it continues throughout a cat’s life, and especially during the next few months. However, getting a start on socialization now is incredibly important to set a kitten up for a successful, fear-free life!
Around week seven, the kittens’ eyes will show their true colors. Some cats’ eyes will remain blue, but most will change to yellow, green, orange, or brown.
During these weeks, kittens typically weigh 650-950 grams.
Weeks 8-12: Finding Forever Homes
Many shelters and rescues will adopt out kittens at eight weeks, though some may wait longer to give them longer to socialize with their mother and siblings.
Adopting an older kitten or cat is fine, of course, but don’t adopt kittens younger than eight weeks. They shouldn’t be separated from their siblings at this age unless it’s strictly necessary, such as if the kitten is orphaned or is having medical challenges that require them to be isolated.
If you’re thinking of adopting a kitten and you don’t already have a cat at home, it’s important to adopt two. They’re social animals, and kittens especially benefit from having other felines in the home.
More and more, rescues and shelters are refusing to adopt out single kittens, as it often leads to behavioral issues and kittens being returned to the shelter.
Even if you do have an adult cat at home, consider adopting two kittens so that they can get out their energy with one another–rather than pestering your older cat!
At eight weeks, kittens are typically around 2 pounds. By 12 weeks, their size will have almost doubled to 3.5-4 pounds.
Check out out kitten growth chart for a week by week breakdown!
Kitten Growth Chart: Week By Week
|Age||Weight Grams||Weight Pounds||Notes|
|Newborn||50-150 g||0.25 lbs||Must stay close to mom|
|1 Week||150-250 g||0.5 lbs||Still blind and deaf|
|2 Weeks||250-350 g||0.75 lbs||Opening eyes and ears|
|3 Weeks||350-450 g||1.0 lbs||Gaining mobility|
|4 Weeks||450-550 g||1.25 lbs||Learning to play|
|5 Weeks||550-650 g||1.5 lbs||Weaning off milk|
|6-8 Weeks||650-950 g||1.75 lbs||Socialization|
|8-12 Weeks||950-2000 g||2-4 lbs||Finding forever homes|
Kittens Can Reproduce as Young as 4 Months
It’s important to have your kittens spayed or neutered before they reach four months of age because this is when they become sexually mature.
Even if you adopt siblings, they will mate with one another. Male kittens still with their mom can even get her pregnant again!
Some people think their cats don’t need to be spayed or neutered if they’re kept indoors and only around other cats of the same sex. However, spaying and neutering also comes with a host of medical and behavioral benefits for your cats. Therefore, it’s highly recommended that you have the procedure done as soon as possible.
It will also give you some extra piece of mind if your kitty escapes the house, and they’re especially likely to try to leave and search for a mate if they’re left intact!
Kittens are Fully-Grown at 1 Year
Most cats are fully grown by the time they reach one year old. Some large breeds, such as Maine Coons, take longer to reach their full size–as many as four or five years!
Despite reaching their full size, one-year-old cats are still essentially kittens. They’re lively, playful, and certainly worth bringing into your home.
Some people refuse to adopt past the cute, 8-week-old kitten stage, but I think this is a huge mistake. Remember, all kittens will grow into adult cats–they don’t stay small forever!
Adult cats are also already socialized and used to living in a home, meaning that they might be an even better fit for your family than kittens!
Frequently Asked Questions
Can you tell how big a kitten will be?
It’s difficult to tell how big your kitten will be as an adult, as sizes range pretty drastically. The average weight of an adult cat is around 10 pounds, but they can also weigh less or much more depending on their physique.
If you know your kitten’s parents, you can use their sizes as an estimate. I don’t recommend going just off of the mother’s size, though–you’ll get a more accurate picture if you’ve seen both parents, as the dad might be way bigger or smaller than the mom.
I took in a small mother cat who had five kittens, and now that they’re fully grown they’re all around double her size. I have a suspicion that the giant tomcat who used to hang around the neighborhood might’ve been their dad, and they seem to have taken after him!
What month do kittens grow the most?
The younger the kitten, the faster they’ll change and grow. Kittens do the most developing during their first month of life. They gain the ability to see, hear, walk, play, and more. See our kitten growth chart above for more specific information.
I found an orphaned kitten! What should I do?
The first step is to determine the age of the kitten. You can use our guidelines above for some helpful hints. For instance, if their eyes and ears are unopened, the kittens are less than 1-2 weeks old. If their eyes aren’t blue, they’re likely over seven weeks old.
It’s also important to get the kitten to a veterinarian, and they’ll be able to tell you their age with more accuracy.
For kittens over eight weeks:
Kittens over eight weeks old can survive without their mothers. They’re also young enough to be spayed or neutered, socialized, and brought indoors, which will provide them with a safer environment to live out their lives.
The next step is to look for other kittens in the area, as there will likely be more where the first one came from!
You can either foster the kittens to find them new homes, contact a rescue who will help to adopt them out, or perform TNR (trap, neuter, and return them outside). Most cats will do better off outdoors than in a shelter unless the environment is very unsafe. Shelter euthanasia rates are unfortunately high.
However, the ideal situation is bringing the kittens indoors and keeping them as indoor-only cats.
For kittens under eight weeks:
If you find a kitten that’s under eight weeks old, please search the area for more kittens or a mother cat. Keep the kitten warm and call a professional for help. You’ll be best off calling a rescue or someone who has experience fostering kittens, as most shelters don’t have resources to provide the 24/7 care that newborn kittens need.
If a mother cat is around, it might be best to let her raise her kittens outdoors. Alternatively, you or another foster could bring her and her kittens indoors and either find them all a home, or return mama to the outdoors after the kittens are weaned and she’s been spayed.
Caring for the kitten(s) on your own is possible, especially if no one in your area will care for them. But, it does require around-the-clock care including regular bottle feedings, stimulating the kittens to use the bathroom, and more. Please do more research if you’re considering this option!
What if I find a litter of kittens without a mom?
If you find a litter of young kittens without mom, she’s likely nearby. Keep an eye on the situation from afar to ensure she returns. Staying too near can scare her off.
Removing the kittens from their mother’s care can result in their deaths, especially if they’re under five weeks old.
Kittens are very fragile at this age, and most mama cats will provide better care than even the most experienced human professionals.
If the mother cat definitely isn’t around, follow the advice above to care for her kittens. If you do find mama, she’ll be able to care for her kittens outdoors. You can wait until they’re weaned, then bring her in to be spayed. The kittens can also be spayed and neutered at eight weeks of age.
Alternatively, you can trap mama and the kittens and bring them indoors, at least temporarily. This allows the mom a safe place to raise her babies before either returning outdoors, or finding a forever home if she’s friendly!