Found a kitten and not sure how old it is? You can get pretty close by checking four things: weight, teeth, eyes and how it moves. Tick what you see below and we’ll give you an age range in weeks, plus a likely birthday.
Kitten age chart, week by week
Weights come from the ASPCA kitten age and weight chart. The other signs come from ASPCA and Alley Cat Allies guides. Every kitten is a bit different, so look at several signs together.
| Age | Weight | Eyes and ears | Teeth | What you’ll see |
|---|---|---|---|---|
| Newborn to 1 week | 70 to 190 g (2.5 to 6.7 oz) | Eyes shut, ears folded flat | None | Crawls, can’t walk. Sleeps, nurses, makes tiny sounds. |
| 1 to 2 weeks | 149 to 295 g (5.3 to 10.4 oz) | Eyes open at 8 to 12 days. Ears start to unfold. | None | Crawls better, kneads and snuggles. |
| 2 to 3 weeks | 198 to 400 g (7 to 14 oz) | Eyes fully open and blue | Tiny front teeth from about 2.5 weeks | Starts to stand. Reacts to sounds. |
| 3 to 4 weeks | 247 to 505 g (8.7 to 17.8 oz) | Ears stand up | Small fangs at 3 to 4 weeks | First wobbly steps, then walks with the tail up. About 1 lb at 4 weeks. |
| 4 to 5 weeks | 296 to 610 g (10.4 to 21.5 oz) | Blue starts changing to adult color | Front teeth and fangs | Runs, plays and pounces. Starts lapping food and using a litter box. |
| 5 to 6 weeks | 345 to 715 g (12.2 to 25.2 oz) | Adult eye color coming in | Back baby teeth from 5 weeks | Eating soft food, very playful. |
| 6 to 7 weeks | 394 to 820 g (13.9 to 28.9 oz) | Adult eye color | Back baby teeth | Looks like a small cat, full of energy. |
| 7 to 8 weeks | 443 to 925 g (15.6 to 32.6 oz) | Adult eye color | All baby teeth in by 8 weeks | About 2 lb at 8 weeks. |
| 10 weeks | About 2.5 lb | Adult eye color | Full set of baby teeth | Weight is still a fair guide up to here. |
| 3 to 4 months | Varies | Adult front teeth from about 12 weeks, adult fangs at 3 to 4 months | Teeth are now the best clue. | |
| 4.5 to 6 months | Varies | Adult back teeth. All adult teeth in by 6 months. | Teenage kitten. |
Sources: ASPCA Kitten Age and Weight Chart (2023), ASPCA Pro, Alley Cat Allies. Chart by CritterCalc.
How to tell a kitten’s age by weight
Under 8 weeks, weight is the quickest clue. Use a kitchen scale that reads grams or ounces. The ASPCA says healthy kittens gain about 7 to 15 grams a day, so a weigh-in each morning also tells you if a young kitten is doing well.
A rough rule from ASPCA Pro: about 1 pound at 4 weeks, 2 pounds at 8 weeks and 2.5 pounds at 10 weeks. After that, kittens grow at different speeds and weight stops being a good guide. A thin or sick kitten will also weigh less than its age, which is why we check other signs too.
How to tell a kitten’s age by teeth
From about 4 weeks to 6 months, teeth are the most reliable sign. Gently lift the upper lip with a clean finger.
- No teeth: under about 2.5 weeks.
- Tiny front teeth only: about 2.5 to 3.5 weeks.
- Front teeth and small fangs: about 3 to 4 weeks.
- Back baby teeth coming in: 5 to 8 weeks. All baby teeth are in by 8 weeks.
- Adult front teeth: about 3 to 3.5 months. They are wider with flat edges. Baby teeth are small and pointy.
- Adult fangs: 3 to 4 months.
- All adult teeth: by about 6 months.
How to tell a kitten’s age by eyes and ears
Kittens are born with their eyes shut and ears folded flat. The eyes start to open at 8 to 12 days and are fully open by about 2 weeks. Every kitten starts with blue eyes. The adult color starts showing at about 4 to 5 weeks. The ears unfold during the second week and stand up at about 3 weeks.
What a kitten needs at each age
Under 4 weeks: warmth, and kitten formula from a bottle if there’s no mother cat. Alley Cat Allies says to feed every 2 hours up to 10 days old, every 3 to 4 hours up to 2.5 weeks, and every 5 to 6 hours up to 4 weeks. Kittens this young also need help to pee and poop after each feed. 4 to 5 weeks: weaning starts. They lap formula, try soft food and learn the litter box. Before 8 weeks: this is the key window for getting kittens used to people, so handle them gently and often. After 8 weeks: time for a vet visit for vaccines and deworming if it hasn’t happened yet.
Once you know the age, our cat calorie calculator works out how much a kitten should eat, and the cat weight chart shows healthy weights as it grows.
Frequently asked questions
How old is a kitten that weighs 1 pound?
About 4 weeks old, for a healthy kitten. ASPCA Pro and Alley Cat Allies both use roughly 1 pound at 4 weeks.
When do kittens open their eyes?
At around 8 to 12 days old. The eyes are usually fully open by 2 weeks. Never try to pry them open.
When do kittens get their adult teeth?
The adult front teeth come in at about 3 to 3.5 months, the fangs at 3 to 4 months and the back teeth from about 4.5 months. All adult teeth should be in by 6 months.
When do kittens start eating food and using the litter box?
At about 4 to 5 weeks, according to Alley Cat Allies. That’s when they start lapping from a dish and trying soft food.
How accurate is a kitten age calculator?
Under 8 weeks it’s usually right within a week or so, especially if you add the weight. After that, teeth give a range of a few weeks. A vet can narrow it down further.
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