Kitten Age Calculator
Found a kitten and not sure how old they are? Estimate their age from weight and development milestones — the same cues shelters and vets use — and get age-appropriate care guidance.
Kitchen scale works — weigh a bowl, zero it, add kitten
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You might also need:Cat Age Calculator·Cat Food Calculator
The pound-a-month rule
cross-checked against developmental milestones
Healthy kittens gain remarkably steadily — about 4 oz per week, one pound per month. A 2 lb kitten is around 8 weeks old (coincidentally the classic adoption age). Milestones refine the estimate: teeth in particular don't lie, which is why vets look in the mouth first.
Kitten development timeline
| Age | Weight | Milestones |
|---|---|---|
| 1 week | 4–8 oz | Eyes closed, ears folded |
| 2 weeks | 8–12 oz | Eyes open (blue), crawling |
| 4 weeks | ~1 lb | Walking well, baby teeth erupting |
| 8 weeks | ~2 lb | Weaned, eye color changing, ready for adoption |
| 3 months | ~3 lb | Full baby teeth, vaccine series underway |
| 4 months | ~4 lb | Adult incisors, teenage energy |
| 6 months | ~6 lb | Most adult teeth, desexing time |
First 48 hours with a found kitten
- Warmth before food: a cold kitten can't digest — warm them gradually first.
- No cow's milk, ever: under ~5 weeks they need kitten milk replacer from a pet store.
- Vet within a few days: for a precise age, parasite check and vaccine plan.
- Once they're established, portion their meals with the cat food calculator (kitten mode) and watch them climb the cat age chart.
Frequently asked questions
How can I tell how old a kitten is?+
Weight is the quickest guide — healthy kittens gain about a pound a month for the first six months, so a 3 lb kitten is roughly 3 months old. Cross-check with milestones: eyes open at 1–2 weeks, walking at 3, weaning at 6–8, and adult teeth arriving from 14 weeks.
How do I age a kitten by their teeth?+
Baby (deciduous) teeth erupt at 2–6 weeks. Adult incisors replace baby ones around 14 weeks, adult canines at 4–5 months, and by 6–7 months a kitten has a full set of 30 adult teeth. A vet can pin the age within a couple of weeks this way.
Why does a rescue kitten’s age matter?+
Age determines everything early on: whether they need bottle feeding (under 4–5 weeks), when vaccines start (from 6–8 weeks), when to desex, and how much food they need. An age estimate within a week or two is good enough for all of these decisions.
What do I feed a kitten at each age?+
Under 4 weeks: kitten milk replacer (never cow’s milk). 4–8 weeks: gruel transitioning to wet kitten food. From 8 weeks: kitten food, 3–4 meals a day. Kittens need roughly 2.5 times the calories per pound of adult cats until about 6 months.
When is a kitten fully grown?+
Most cats reach adult size around 10–12 months, though large breeds like Maine Coons keep growing to 3–4 years. Switch from kitten to adult food at about 10–12 months for typical cats.