How to Tell a Kitten's Age: Week by Week Signs
Key takeaways
- A kitten's age is estimated from a stack of clues together: eyes and ears, teeth, body weight, and how steady it is on its feet, not from any one sign alone.
- Useful rules of thumb: eyes open at about 7 to 14 days, ears unfold by around 3 weeks, baby teeth erupt from about 3 to 4 weeks, and a healthy kitten gains roughly 100 grams a week, near enough 1 pound a month.
- Age changes the care plan: feeding, worming, the first vaccinations, and neutering are all timed to a kitten's age in weeks, so an estimate guides the whole early routine.
- If you are unsure, your vet can age a kitten more accurately from its teeth and weight and start the right schedule; this matters most with rescued or orphaned litters.
You tell a kitten’s age by reading several clues together: the eyes and ears, the teeth, the body weight, and how steady the kitten is on its feet. No single sign is exact, but stacked up they place most kittens within a week or two, which is close enough to start the right feeding, worming, and vaccination plan.
I learned this the hard way when a tiny ginger kitten turned up under our shed, eyes barely open and ears still flat. Knowing roughly how old he was told me everything: that he still needed bottle feeds, that he was too young to leave a mother, and that the vet visit was urgent rather than optional. Here is how to read the same clues yourself.
Why a kitten’s age matters
Knowing a kitten’s age matters because almost every early care decision is timed in weeks. Feeding amounts and food type, the first deworming, the primary vaccination course, microchipping, and neutering are all scheduled by age, not guesswork. Cats are classed as kittens from birth to about 1 year under the AAFP and AAHA life stage framework, but the first 12 weeks are where the timings are tightest. Neutering, for example, is commonly done from around 4 months, so an accurate age keeps the whole calendar honest. If you have just taken on a stray litter, our guide to settling in a nervous newcomer walks through the first days alongside this.
Eyes and ears: the first two weeks
A kitten’s eyes and ears are the quickest read for the youngest stage. Newborns are born with eyes sealed shut and ears folded down flat against the head. Most kittens open their eyes between about 7 and 14 days old, and those first eyes are a cloudy blue that only settles into the adult colour over the following weeks. The ears begin to unfold from around 2 weeks and stand up properly by about 3 weeks. So a kitten with shut eyes and flat ears is almost certainly under two weeks old, while open blue eyes and lifting ears point to roughly two to three weeks.
Teeth: the most reliable clue
Teeth give the single most reliable age estimate, especially past three weeks. Kittens have no visible teeth at birth. The small baby (deciduous) teeth start erupting from about 3 to 4 weeks, beginning with the tiny front incisors, and a full set of 26 baby teeth is usually in place by around 6 weeks. From about 3 to 4 months those baby teeth start falling out as the adult set comes through, finishing at roughly 6 months with 30 adult teeth. So sharp little baby teeth with no gaps suggest six weeks to three months, while a mouth losing baby teeth and growing larger adult ones suggests three to six months. If you want certainty, this is the clue a vet will check first.
Weight: a number you can track
Weight gives you a number to cross-check the other signs against. As a rough guide a healthy kitten gains about 100 grams a week, which works out near 1 pound a month, so for the first few months weight in pounds loosely tracks age in months: about 1 pound at 4 weeks, 2 pounds at 8 weeks, and 3 pounds at 12 weeks. A set of digital kitchen scales is more than accurate enough at home. Weight is only a guide because build, breed, and health all shift the number, so it is most useful watched as a trend: a kitten that is steadily gaining is on track, while one that has stalled needs a vet, whatever its apparent age.
Mobility and behaviour: how it moves
How a kitten moves and plays fills in the gaps between the physical markers. At under two weeks a kitten can barely lift its head and wriggles rather than walks. From about 3 weeks it starts to stand and take wobbly steps; by 4 weeks it is walking and beginning to play. By 6 to 8 weeks kittens are running, climbing, pouncing, and using a litter tray, and they are eating solid food well by around 8 weeks. Confident, playful, fully coordinated movement points to eight weeks or more. This matters for rehoming: kittens should normally stay with their mother and litter until at least 8 weeks, and many shelters rehome at 12 to 13 weeks.
Putting the clues together
Read the signs as a set, not in isolation, and let them agree. Shut eyes and flat ears with a wriggling body mean a newborn under two weeks. Open blue eyes, lifting ears, and the first teeth coming through mean three to five weeks. A full set of baby teeth, steady walking, play, and around 1 kilogram of body weight mean roughly eight to ten weeks. Once you have a working estimate you can match the right food and portions to the age and book the first vet visit with confidence. When the clues disagree, trust the teeth and the weight trend, and let your vet settle it.
This guide is general information, not a diagnosis. A vet can age your own kitten far more accurately in person and start the correct feeding, worming, and vaccination schedule, so have any kitten checked over by your own vet.
References
- Caring for a kitten, International Cat Care.
- Cornell Feline Health Center, Cornell University College of Veterinary Medicine.
- Life Stage Definitions, American Association of Feline Practitioners.
- Kitten care, ASPCA.
Frequently asked questions
How can I tell how old my kitten is?
Combine several signs rather than relying on one. Closed eyes and folded ears suggest under two weeks; open blue eyes with the kitten starting to wobble around suggest two to four weeks; sharp baby teeth, steady walking, and play suggest about four to eight weeks. Weight helps too: a healthy kitten gains roughly 100 grams a week, so a 1 kilogram kitten is often near 8 to 10 weeks old. Your vet can refine the estimate from the teeth.
At what age do kittens open their eyes?
Most kittens open their eyes between about 7 and 14 days old, and the eyes stay a cloudy blue at first. If a kitten's eyes are still firmly shut, it is usually under two weeks old. The adult eye colour only settles in over the following weeks, so blue eyes alone do not tell you the breed or the final colour.
How can I tell a kitten's age from its teeth?
Teeth are one of the most reliable age clues. Kittens have no visible teeth at birth; the small baby (deciduous) teeth start coming through from about 3 to 4 weeks, and a full set of 26 baby teeth is usually in by around 6 weeks. Adult teeth then replace them from about 3 to 4 months, so a kitten losing baby teeth and growing larger adult ones is usually three to six months old.
How much should a kitten weigh for its age?
As a rough guide a healthy kitten gains about 100 grams a week, which works out near 1 pound a month, so weight roughly tracks age in pounds for the first few months: about 1 pound at 4 weeks, 2 pounds at 8 weeks, 3 pounds at 12 weeks. This is only a guide; build, breed, and health all affect weight, so weigh against the trend over time rather than a single number.
When can a kitten leave its mother?
Kittens should normally stay with their mother and litter until at least 8 weeks, and many shelters and breeders rehome at 12 to 13 weeks. Before then they are still feeding, learning social skills, and building immunity. Knowing a kitten's age tells you whether it is ready to leave, and whether a very young one needs bottle feeding and extra warmth.
Why does my kitten's age matter for its care?
Age sets the whole early routine. Feeding amounts and food type, the first deworming, the primary vaccination course, microchipping, and neutering are all timed in weeks. Getting the age roughly right means the kitten is fed correctly and protected on schedule rather than too early or too late.
Written by Hannah Reeves. Reviewed by Dr Sarah Whitfield, BVSc MRCVS.
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