How old is my kitten?
Weight, teeth and eyes each narrow it down. Enter what you can see and the estimator finds the age where the clues agree, using the ASPCA's kitten chart.
Kitten age chart, weeks 1 to 8
The weights are the ASPCA's ranges, from the lowest weight on the first day of each week to the highest on the last. The teeth and eyes are the ASPCA's milestones; the last column is from Alley Cat Allies' week-by-week kitten guide.
| Age | Weight | Teeth | Eyes | What else you'll see |
|---|---|---|---|---|
| Week 1 days 1–7 | 70–190 g 2.5–6.7 oz | None | Closed | Ears folded; can't stand; eyes start to open near the end of the week |
| Week 2 days 8–14 | 149–295 g 5.3–10.4 oz | None | Opening | Ears almost uncurled; starts to crawl |
| Week 3 days 15–21 | 198–400 g 7.0–14.1 oz | Baby incisors | Open, blue | Walking more steadily; ready to try a litter box and wet food |
| Week 4 days 22–28 | 247–505 g 8.7–17.8 oz | Baby canines | Open, blue | Ears fully up; sturdy on its feet; plays with littermates |
| Week 5 days 29–35 | 296–610 g 10.4–21.5 oz | Baby premolars, lower jaw | Changing color | Sight fully developed; runs and plays hard; tries solid food but still nurses |
| Week 6 days 36–42 | 345–715 g 12.2–25.2 oz | Baby premolars, upper jaw | Changing color | Uses the litter box and eats cat food; grooms itself and littermates |
| Week 7 days 43–49 | 394–820 g 13.9–28.9 oz | All baby teeth | Adult color | Almost fully weaned |
| Week 8 days 50–56 | 443–925 g 15.6–32.6 oz | All baby teeth | Adult color | Fully weaned |
Sources disagree by about a week on the teeth: Cornell says baby teeth start at about 4 weeks and are all in by about 6 weeks, VCA says from about 3 weeks until 6 to 8 weeks. That's one reason to use more than one clue.
Why one clue isn't enough
The weight ranges overlap a lot. A 400 g kitten could be anywhere from day 21 to day 43 on the ASPCA chart, three weeks apart. Teeth and eyes each cover a week or two. Put together, they usually narrow the age to a week or so, which is how the estimator above works: it lists the range each clue allows and shows where they overlap.
A kitten that has been underfed or ill can be small for its age and still have the teeth of an older kitten. When the clues disagree, the teeth and eyes are usually the better guide, and a veterinarian can check.
After 8 weeks: the adult teeth
The ASPCA chart stops at 8 weeks, and by then weight varies too much to say much on its own. The teeth still help. Kittens have 26 baby teeth and adult cats have 30. VCA says the adult teeth replace the baby teeth from about 10 weeks to 6 months, starting with the incisors at the front, and most kittens have all 30 by 6–7 months; Cornell puts it at about six months. So a kitten with bigger adult incisors coming in is likely between about 10 weeks and 6 months old, and one with a full adult set is about 6 months or older.
Eye color helps only until about 2 months: kittens' eyes are blue at first, and Alley Cat Allies notes that the true color may not show until about two months of age.
How to weigh a kitten
A kitchen scale that reads in grams is precise enough. Weigh at about the same time each day and write it down: the trend tells you more than one number. On the ASPCA chart, normal kittens gain 7–15 g a day.
Keep a record
Once you know roughly when your kitten was born, add it in My pet with an estimated birth date. The other tools then fill in its age, such as the age in human years (from 1 year) and the kitten weight chart.
Questions owners ask
How can you tell how old a kitten is?
Use several clues together: weight, which teeth have come in, and the eyes. The ASPCA's chart pairs a weight range for each day of the first 8 weeks with teeth and eye milestones, and says to use weight together with the milestones.
How much should a 4-week-old kitten weigh?
On the ASPCA chart, a kitten in week 4 (days 22–28) weighs 247–505 g, about 8.7–17.8 oz. Normal kittens gain 7–15 g a day.
When do kittens open their eyes?
The ASPCA chart shows eyes closed in week 1, opening in week 2, and open and blue in weeks 3–4. The color starts to change in weeks 5–6 and reaches its adult shade in weeks 7–8.
When do kittens get their teeth?
Baby incisors come in during week 3, canines in week 4 and premolars in weeks 5–6, with all baby teeth in by week 7 (ASPCA). Adult teeth replace them from about 10 weeks, and most kittens have all 30 by 6–7 months (VCA).
How old is a kitten that weighs 1 pound?
One pound is about 454 g. On the ASPCA chart that weight fits anywhere from day 25 (week 4) to day 51 (week 8), so check the teeth and eyes to narrow it down.