Are you considering adopting or fostering a newborn kitten? If so, make sure you know what age they are. But how to tell a kittens age?

Kittens have very specific needs at each stage of their development. Not having these needs met can have devastating consequences for their health and mental well-being.

For instance, cats that get separated from their mother too soon often lack proper grooming skills, are more skittish or become outright aggressive.

They also haven’t had a chance to get all the necessary antibodies from their mother’s milk, which leaves them vulnerable to all kinds of diseases later in life. If you suspect your kitten to need some extra nutritional support, consider given them a kitten milk replacer with probiotics or colostrum to boost their immune system and digestive tract. And make sure they are up-to-date on their vaccinations.

We have 4 easy ways to help you determine exactly how old your kitten is, and whether or not it is ready to be adopted.

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How To Tell A Kittens Age By Their Eyes

The first, and most obvious, way how to tell a kitten’s age is by looking at their eyes.

When a kitten is first born, its eyes are fully closed. They stay this way for the first week.

At the beginning of the second week, a kitten’s eyes will start to open. It usually takes around 2 to 4 days before they are fully open and peering out into the world. At this stage, your kitten’s eyes will be pale blue.

Their vision won’t be that great, though. A kitten’s eyesight and visual coordination can take up to 10 weeks to fully develop.

Finally, when your kitten is 7 weeks to 2 months old, their adult eye color will start to come out. Keep in mind that some cats keep their blue eye color. This mostly occurs in lighter coated cats, like Ragdolls, who are known for their piercing blue eyes.

How To Tell A Kittens Age By Their Weight

When you take your newborn kitten to the veterinarian’s office, the first thing the vet will do is put them on a scale. That’s because your kitten’s weight is the most reliable, and most precise, way to tell its age and progression.

On average, a kitten steadily gains about 1 pound (450 grams) every month for the first 5 months. Divided by 30, that comes to about 0.5 ounces (15 grams) a day.

Of course, some variation is expected depending on your kitten’s breed and background. But overall, weight is a good indicator of a kitten’s state of development.

How To Tell A Kittens Age By Their Teeth

Another way to tell a kitten’s age is by looking at its teeth and how far they have developed.

Kittens start teething when they are around 3 weeks of age.

The first teeth that come in are baby teeth. These are very small and pointy.

When your kitten is about 3 months old, its baby teeth will be gradually replaced by adult teeth. These are a bit bigger and wider, with flatter edges.

Kittens are generally done teething at 4 months old.

How To Tell A Kittens Age By Their Behavior

In terms of behavior, a kitten’s walking skills and playfulness are good measures of their maturity.

When they are only a week old, kittens will spend about 90% of their time sleeping, and the other 10% eating.

During their second week, they will start to move around a bit, though never too far from their mother and siblings.

When they are 3 to 4 weeks old, kittens will become more confident walking around and discovering their surroundings. It is around this time that you will start to see them interact with their siblings more and show first signs of playful behavior.

After 4 weeks, your kittens will be getting more and more playful, not just with their siblings, but also with toys and humans.

Final Thoughts

A good start is half the battle. That’s true for most things, including your cat’s health.

Knowing the exact age of your kitten is a great help in tracking its development over time, and spotting any problems as early as possible. It will also help you preventing kittens from being separated from their mother too soon.

That said, there are differing guidelines when it comes to determining when a kitten is ready to be weaned from its mother. Some say 12 weeks, others say it’s as soon as 6 weeks.

Personally, I have found that it differs from cat to cat. Some simply are more confident and more eager to venture out on their own. Others need a bit more reassurance from their mom before they are ready.

Mom’s personality also comes into play here. I have had mother cats who couldn’t wait to wean their kittens as soon as they started teething, only for another mother cat to step in and take over.

My best advice is to consider each case individually. Is your kitten still clinging to mom and not venturing out much? Then it’s best to not separate them yet.

Is your kitten eating solids, walking confidently and running after its siblings without much care? Then they are ready to be adopted!