Kitten Age Chart: Week-by-Week Development and Care Guide

Whether you've found an orphaned kitten outside or brought home a new litter, knowing how old a kitten actually is makes a real difference in how you care for them. A kitten age chart gives you a practical reference point: what physical traits to look for, what developmental milestones to expect, and what feeding approach fits the stage they're in. This guide covers it all, from the first days of life through the transition to a fully weaned kitten ready to go to a new home.

How to Use a Kitten Age Chart to Estimate Age

If you've found a kitten and don't know when they were born, you can make a reasonably accurate estimate by looking at a few physical markers. Eyes, ears, teeth, and body weight each tell you something specific. One more clue in the very first days: a newborn kitten may still have an umbilical cord stump attached. The umbilical cord stump typically dries and falls off around three days of age, so a kitten with one still present is almost certainly under a week old.

Eyes

Newborn kittens are born with their eyes shut. They typically begin to open around 8 to 10 days of age, starting as a narrow slit. By two weeks, eyes are fully open and always a bright baby blue. Those blue eyes are a giveaway that a kitten is still young: at around seven weeks, the permanent adult eye color starts to come through. So a kitten with grey, green, or yellow eyes is likely at least seven weeks old, while a kitten with closed eyes is under ten days.

According to Alley Cat Allies, eye color is one of the most reliable age indicators in very young kittens, and the transition from blue to adult color tracks closely with weeks six through eight.

Ears

At birth, a kitten's ears are folded flat against the head. Around week two, the ear canals begin to open, and the pinnae (the outer ear flap) start to unfold. By week three, the ears stand upright, giving the kitten that classic alert, triangular look. A kitten with fully erect ears and open canals is likely at least three weeks old.

Teeth

A kitten's first teeth, the tiny incisors at the front of the mouth, begin pushing through the gums around week three. The canine teeth (the longer, pointed fangs) come in next, around week four, followed by the premolars. The full set of baby teeth is usually complete by seven to eight weeks. Permanent adult teeth start replacing baby teeth between three and four months of age. Baby teeth are smaller and noticeably more pointed. If you see larger, flatter teeth, the kitten is probably at least three to four months old.

Weight

A healthy newborn kitten weighs roughly 50 to 150 grams at birth. Weight gain is fast in the first weeks: most kittens double their birth weight within the first week or so. A reliable rule of thumb from Kitten Lady is that a one-pound kitten is approximately four weeks old, and a three-pound kitten is around 12 weeks old. This isn't exact, especially for kittens who have had nutritional setbacks, but it's a useful starting point when other markers are unclear.

Kitten Age Chart: Week-by-Week Milestones

This table covers the key changes across the first twelve weeks of life. Use it as a quick reference alongside the physical markers above.

Age	Eyes	Ears	Teeth	Weight (approx.)	Mobility	Feeding
Newborn (0–3 days)	Closed	Folded flat	None	50–150 g	None (sleeps, nurses)	Mother's milk or KMR only
Week 1	Closed	Folded	None	~100–200 g	Crawls slightly	Mother's milk or KMR only
Week 2	Beginning to open (slit)	Beginning to unfold	None	~200–300 g	Wobbly crawling	Mother's milk or KMR only
Week 3	Fully open, baby blue	Upright	Incisors emerging	~300–400 g	Wobbly walking	KMR + beginning of gruel
Week 4	Open, blue	Fully upright	Canines emerging	~400–550 g	Walking, short runs	Wet food gruel 4x/day
Week 5	Blue fading	Full	Baby teeth mostly in	~550–700 g	Running, playing	Wet food gruel/softened kibble
Week 6	Adult color emerging	Full	All baby teeth present	~700–850 g	Running, coordinated	Soft wet food 3x/day
Week 7	Adult color transitioning	Full	Full baby set	~850 g–1 lb	Active, jumping attempts	Wet or wet/dry combo 3x/day
Week 8	Adult color settled	Full	All baby teeth present	~1–1.5 lbs	Fully mobile	Wet or dry kitten food 3x/day
Weeks 9–12	Adult color	Full	Baby teeth complete	~1.5–3 lbs	Highly active	Kitten food 3–4x/day
3–4 months	Adult color	Full	Adult teeth replacing baby	~3–4 lbs	Full kitten energy	Kitten food 3x/day

Weights are approximate ranges for kittens with adequate nutrition. A kitten consistently below the lower end of the weight range for their age is worth a vet check, especially in the first few weeks when nutritional deficits can compound quickly.

What to Feed a Kitten at Each Stage

Feeding changes significantly across the first twelve weeks. Getting this right supports healthy weight gain, proper organ development, and a digestive system that transitions smoothly to solid food.

Newborn to Week 3: Milk Only

Very young kittens depend entirely on their mother's milk or a commercial kitten milk replacer (KMR). Never give cow's milk to kittens. It lacks the nutrients they need and commonly causes diarrhea. If the mother is unavailable, a commercial KMR formula is the appropriate substitute. The Cornell Feline Health Center recommends feeding orphaned kittens every two to three hours around the clock in the first weeks of life.

Neonatal kittens also cannot regulate their own body temperature and cannot urinate or defecate without stimulation. If you are hand-raising a litter, this is a significant care commitment that starts with choosing a kitten milk replacer formula and preparing it safely.

Weeks 3 to 6: Gruel and Transition Foods

Around week three, kittens can begin the weaning process. The standard approach is to mix a small amount of high-quality wet kitten food with warm KMR or water to create a soft gruel. This gives kittens something to lap from a shallow dish, which they'll figure out with some encouragement and a fair amount of mess.

Start with four small meals a day. By week six, most kittens are eating gruel with much less KMR mixed in and can handle soft wet food more directly. Some kittens progress faster than others. Follow the kitten's lead rather than a strict schedule, and keep milk available from the mother or supplemented until the transition is complete.

Weeks 6 to 12: Kitten Food

By six to eight weeks, most kittens are fully or nearly weaned and eating soft kitten food at regular meals. Three to four meals a day is appropriate for young kittens since their stomachs are small and their energy needs per pound of body weight are high.

From eight to twelve weeks, a kitten typically eats one to one and a half 3-ounce cans of wet food per day, split across three or four meals. If you're feeding dry food, choose a formula specifically designed for kittens, not adult cats, since kittens need more protein and fat per calorie than adults. Offering wet food as at least part of the diet is generally recommended by veterinarians because it naturally supports hydration and is easier to digest.

Kittens who seem hungry after meals or aren't gaining weight steadily are worth checking with a vet, since there are several common reasons kittens fall behind on weight gain even when they appear to be eating.

Supporting Nutrition During the Transition

Young kittens going through weaning can sometimes experience soft stools or a mild digestive upset as their systems adapt to new food. This is common and usually short-lived. If it persists or worsens, there are gentle, supportive steps to help a kitten with diarrhea feel better.

For kittens who need a nutritional boost during weaning (or anytime in the early months), Under The Weather's Ready Cal kitten supplement is a high-calorie formula designed to support healthy weight gain in young cats. It's formulated for easy administration, which matters when you're dealing with a small kitten who may not be eating consistently yet.

When Can Kittens Leave Their Mother?

This question comes up often, especially when breeders or rescue organizations are placing kittens. The general answer is eight weeks as an absolute minimum. Veterinarians and animal behaviorists generally recommend 12 weeks as the optimal target.

The reason twelve weeks matter is behavioral, not just physical. Between eight and twelve weeks, kittens are in a critical socialization window. They learn bite inhibition, litter box habits, and how to interact with other cats and people. Kittens separated from their mother and littermates before this window closes are statistically more likely to exhibit behavioral issues in adulthood, including fearfulness, aggression, and difficulty adapting to new situations.

Research cited by Cats.com notes that weaning as late as 12 to 14 weeks may yield better long-term behavioral outcomes than the traditional 8-week guideline. If you have the option to keep kittens with their mother through twelve weeks, it's worth doing.

A kitten who comes to you before eight weeks (whether found outdoors or obtained from an early-weaning situation) will need more intensive care and socialization to compensate for what they missed. That includes more frequent handling, gentle play that teaches bite limits, and extra patience during the adjustment period.

What the Kitten Age Chart Means for Day-to-Day Care

Knowing roughly how old a kitten is shapes almost every care decision in the early weeks: how often to feed, what to feed, when to start socializing in earnest, and when to schedule the first vet visit.

A few practical notes:

• First vet visit: Plan this at or before eight weeks. Your vet will confirm age, check weight, begin the vaccination series (first vaccines are typically given between six and eight weeks), and discuss deworming. The ASPCA recommends starting vaccines around six to eight weeks and continuing boosters on a schedule through sixteen weeks.
• Deworming: Kittens are commonly dewormed starting at two weeks of age (or at the first vet visit for found kittens), with repeat treatments every two weeks until broad-spectrum parasite prevention can begin.
• Litter box: Most kittens are using a litter box reliably by five weeks. Offer a shallow pan with unscented litter in an accessible spot. If your kitten came from the mother, she will have already started teaching them.
• Handling and socialization: The socialization window peaks between two and seven weeks. Gentle daily handling during this period makes a measurable difference in how comfortable a kitten is with humans as an adult. If the kitten was not handled early, that doesn't mean socialization is impossible, just that it takes more time and consistency.

Kittens growing up on track with the milestones in this chart are generally healthy and developing well. The ones who stand out as needing attention are those who are significantly underweight for their age, showing no interest in food during the weaning window, or lagging noticeably behind on motor skills or responsiveness.

Supporting Kitten Health Through Every Stage

Young kittens have significant nutritional demands packed into a small, fast-growing body. Most healthy kittens raised on good kitten food and their mother's milk will thrive without supplementation. But there are situations where extra support makes a difference: kittens who were underweight at birth, orphaned kittens raised on formula, kittens recovering from illness, or kittens going through a rough weaning transition.

For those situations, a high-calorie supplement like Under The Weather's Ready Cal for kittens can help fill the gap. It's designed to support energy intake and healthy weight gain in kittens who need a little extra. Pair it with good kitten food and close monitoring, and you'll have a much clearer picture of whether a kitten is getting what they need. There's a broader context for what to look for in kitten supplements as a young cat grows.

Most kittens who get appropriate care in the first twelve weeks go on to be resilient, social, healthy adult cats. The early work is real, but it pays off throughout the cat's life. If you have questions about a specific kitten's progress, a vet is always the right call. This chart provides a reference, but your vet provides context specific to your kitten's situation.

Browse Under The Weather's kitten supplement line if you want to see what's available for supporting a young cat through the early months.