Free kitten age calculator
Found a kitten, or not sure how old yours is? Tick what you can see (teeth, eyes, ears, how they move) and we’ll estimate the age in weeks, a likely birthday and what your kitten needs right now. The week-by-week kitten age chart is just below.
Once you know the age, check how to tell if a kitten is a boy or girl and what kittens eat at each age.
Reviewed October 2026 · By Shoaib A. · See sources
Your kitten's age estimate will appear here.
Plus a likely birthday, what stage they're in and what they need right now.
Quick answer
To tell a kitten’s age, check the teeth first, then the eyes, ears, weight and how the kitten moves. Newborns have closed eyes and folded ears. Eyes open at about 1–2 weeks, baby front teeth appear around 3 weeks and fangs around 4. Kittens weigh about 100 g at birth and gain about 100 g a week, reaching roughly 2 lb (900 g) at 8 weeks.
Week by week
Use this chart alongside the calculator above. Find the row that matches most of what you see. If signs disagree, trust the teeth and the overall picture over any single clue.
Step by step
Shelters and rescues age kittens by putting several clues together. Here is the order that works best at home:
The umbilical cord is a useful clue for the very youngest kittens: it dries within a day or so and usually falls off between about day 2 and day 5 (Maddie’s Fund; Kitten Lady). Never pull it off.
Most reliable clue
Teeth erupt in a predictable order, which makes them the best age marker from about 4 weeks until all the adult teeth are in. Kittens grow 26 baby (deciduous) teeth and later 30 adult teeth (VCA Animal Hospitals).
Sources disagree by a week or two on exact timing. For example, the Merck Veterinary Manual puts the first baby incisors at 2–4 weeks and Alley Cat Allies at 2.5–3.5 weeks, and adult teeth may start anywhere from about 3 to 4 months (Merck; VCA). Breed, nutrition and health all shift the timing a little, so treat the age as a range.
Use with care
A common shelter shortcut is that kittens weigh about 1 pound per month of age (ASPCApro). For tiny kittens the gram version works well: about 100 g at birth plus roughly 100 g each week.
But weight gets less reliable as kittens grow. A 2020 study of pet kittens found the 1-pound-per-month rule guessed age within a week for about two thirds of kittens at 8 weeks, but for fewer than half at 12 weeks and under a fifth at 20 weeks. It also tended to underestimate the age of males (DiGangi et al., Journal of Feline Medicine and Surgery). So after about 10 weeks, put more trust in the teeth.
Want to check whether your kitten’s weight is on track for their age? Use our kitten weight chart and growth checker.
Eyes and ears
Eyes and ears are most useful in the first 3 weeks. Eyes start opening between about 8 and 12 days, though some open as early as day 5 or as late as day 14. They are always blue at first and vision is blurry for a while (Kitten Lady; Maddie’s Fund).
Eye color changing from blue to green, yellow, copper or gray is a later clue, but sources disagree on when it happens: Alley Cat Allies says about 4–5 weeks, while Kitten Lady and PetMD say about 7–8 weeks (Alley Cat Allies; PetMD). In practice, a kitten whose eyes are clearly not blue anymore is usually at least 6–7 weeks old.
Ears are folded flat at birth, open and look small and rounded at about 2 weeks, and stand upright from about 3 weeks (Best Friends Animal Society).
Why it matters
Age decides almost everything about care in the first weeks:
Kitten Lady notes that at about 8 weeks and 2 lb, many kittens are big enough for spay/neuter surgery and adoption (Kitten Lady). Your vet will set the exact timing. To turn your kitten’s age and weight into daily portions, use the kitten feeding calculator.
Be safe
Call your vet or local rescue the same day if a kitten under 8 weeks:
Very young kittens can go downhill within hours. If you found a kitten outside, check first whether mom is nearby: she may come back. Our newborn guide explains how to keep a kitten warm and fed in the meantime.
Check the teeth first, then the eyes, ears, weight and how the kitten moves. Closed eyes mean under about 2 weeks, tiny front teeth mean about 3 weeks, pointy canines about 4 weeks, and a full set of baby teeth about 8 weeks. The calculator at the top of this page combines these clues for you.
A healthy 8-week-old kitten usually weighs about 850–950 g, or about 2 pounds. It has all 26 baby teeth, adult eye color, upright ears, and eats solid food on its own.
Usually about 450–550 g, or roughly 1 pound. At this age kittens have pointy canine teeth, walk confidently and are starting to wean.
Yes. Teeth are the most reliable clue from about 4 weeks to 6 months. Baby incisors appear at about 3 weeks, canines at about 4 weeks and premolars at 5–8 weeks. Adult teeth start coming in at about 3–4 months and are all in by about 6–7 months.
Most kittens open their eyes between about 8 and 12 days old, though anywhere from day 5 to day 14 can be normal. Their eyes are always blue at first.
Sources differ: some say from about 4–5 weeks, others 7–8 weeks. If a kitten’s eyes are clearly green, yellow, copper or gray rather than blue, it is usually at least 6–7 weeks old.
Only for young kittens. Research on pet kittens found the rule works reasonably up to about 8–10 weeks but becomes unreliable after that, and it tends to underestimate the age of males. Use the teeth for older kittens.
By about 6–7 months all 30 adult teeth are in, so the teeth stop being a precise clue. From then on, a vet can estimate age from the teeth’s wear, growth plates and overall development.
