How to Estimate a Kitten’s Age: Teeth, Eyes, Weight
A kitten’s eyes open at about two weeks, its first teeth arrive from roughly three weeks, and its weight climbs by about 100 grams for every week of age, so a kitchen scale tells you more than a guess. Read together, those three markers usually place a stray kitten within a week or two of its real age. Read alone, any one of them can mislead, because litters vary and a hungry kitten grows on a different curve from a well-fed littermate.
Suppose a neighbour hands you a box with three kittens in it and asks how old they are. The mother is nowhere in sight and nobody wrote down a date. What you can do is record what you see tonight, repeat the check in a week, and let the change tell you more than any single snapshot. A vet can then confirm the estimate and set the vaccination and worming schedule, which is the part that actually matters.
Eyes, Ears, and the First Two Weeks
Kittens are born with their eyes shut and their ears folded flat. The eyes usually begin to open around seven to ten days and are open in most kittens by about two weeks, though an individual can lag several days behind its littermates. They stay blue and unfocused for a while after that, and adult colour settles in over the following weeks, so a kitten with cloudy baby-blue eyes is usually under two months old.
The ears follow a similar timetable. They lift and unfold during the second week and point forward by about three weeks, which is also when a kitten starts turning its head toward a sound. A kitten with shut eyes and flat ears is in its first fortnight, not its first month. If one eye stays sealed while the other opens, or both are crusted, that is a reason to see a vet rather than to keep guessing.
Teeth Are the Closest Thing to a Birth Certificate
Dental development is the most reliable clock a kitten carries. The baby incisors, the small front teeth, usually come through between two and four weeks, and most guides settle on about three weeks as the point when you can feel them. The canines follow at three to four weeks and the premolars at four to six. By six to eight weeks the full set of 26 baby teeth is normally in place.
Then the timetable shifts to replacement. At around three to four months the adult incisors begin to push through and the baby teeth loosen. By five to six months the adult canines and premolars have arrived, and the mouth holds its full 30 teeth. A kitten in the middle of the swap often shows a double canine, one small tooth beside a larger one, and chews more than usual. That is normal. A baby tooth that stays put while the adult grows in beside it is not, and should be shown to a vet.
Two cautions. Do not pry a kitten’s mouth open; the section below describes a gentler method. And do not read these numbers as a diagnostic chart. A kitten born small, or one that has been ill, can run days behind its littermates, so teeth give you a range rather than a timestamp.
Weight: About 100 Grams for Every Week
Healthy kittens gain weight in a fairly straight line, and the rule of thumb is about 100 grams of body weight for each week of age. A two-week-old sits near 200 grams, a four-week-old near 400, an eight-week-old near 800. Birth weight clusters around 90 to 110 grams depending on litter size and the mother’s condition, so the starting point varies more than the slope does.
The rule describes typical growth; it does not govern it. Big males and large-breed cats run ahead of it, and the runt of a large litter can sit below it for weeks and still be healthy. The direction of travel carries more information than the absolute number. Weigh at the same time each day on a scale that reads in grams and watch the line; a kitten age calculator turns the same numbers into weeks and months you can compare against the 100-gram rule. A kitten that holds its weight for two days, or loses any, needs a vet promptly, because a small body has very little reserve.
Coat and Behaviour Fill In the Edges
Fur and movement fill in what eyes and teeth leave blurry. A kitten’s coat is short and close for the first weeks and starts to look fuller from around six to eight weeks. Long-haired cats may not show their full coat for months, which is one reason coat length is a weak age marker on its own.
Behaviour is more useful. At two weeks a kitten crawls and paddles. At three it can stand, wobble forward and hiss. By four weeks it walks with reasonable control and plays with its littermates. At five to six weeks it runs, pounces and climbs badly. Between six and eight weeks it spends most of its waking hours in play, which is also the window when handling by different people has the most lasting effect.
One honest limit: behaviour bends with stress. A frightened kitten can look younger than it is, and a bold one can look older. Use it to confirm the other markers, not replace them.
How to Check a Kitten Without Stressing It
Run the checks in the same order each time and write the results down with the date. Two quiet minutes beat a long examination.
- Weigh first, before a feed, on a kitchen scale in grams.
- Look at the eyes without touching them, and note whether both are open and clear.
- Lift the lip with a fingertip instead of opening the mouth.
- Check the ears for position and the coat for bare patches or fleas.
- Watch the kitten walk and play for a minute before you pick it up.
Then stop. Do not bathe the kitten, do not trim anything, and do not offer solid food to one whose eyes are still shut. Feeding decisions belong with the vet who examines the animal, because a three-week-old and a six-week-old need different food in different amounts.
Take the notes to the first appointment. The vet will weigh the kitten, check hydration, look for parasites and congenital problems, and estimate age from the same markers plus experience. Ask for the estimated birth date to be written in the record. Every later vaccination, worming and neutering decision runs from that date, and the cat age calculator can convert it to human-equivalent years at any point. Ask which life stage the kitten is in; the FelineVMA guidelines cover exactly that.
FAQ
Can I tell a kitten’s age from a photo?
Only loosely. A photo shows whether the eyes are open, how the ears sit, and how big the kitten looks beside a familiar object. It cannot show weight. Treat an estimate from a picture, including one from a cat age from photo tool, as a starting range to confirm in person.
Do all kittens follow this schedule?
No. The order is consistent; the timing shifts by days or weeks with litter size, birth weight, nutrition and illness. That is why every milestone here is a range, and why a vet should confirm any estimate you plan to act on.
At what age can a kitten leave its mother?
International Cat Care notes that pedigree kittens are usually rehomed after 12 weeks, while domestic kittens may go at around eight. Separation before eight weeks is a welfare concern, not a shortcut, and 10 to 12 weeks is easier on the kitten.
What if the mother is still nursing?
Watch her as well as the kittens. When she stops lying down to feed, and when she starts carrying food to the nest, both track the kittens’ age. Keep weighing anyway; the number is harder to argue with.
Last updated: October 26, 2026. This article is for general information only and is not medical, veterinary or legal advice. For decisions about your own health, your pet, or a legal matter, consult a qualified professional.
Sources
- International Cat Care, Choosing a kitten: icatcare.org
- FelineVMA (formerly AAFP), Practice Guidelines: catvets.com
