CatYearsKitten age calculator
A kitten’s first months move at toddler speed: 2 months ≈ 2 human years, 3 months ≈ 4, 6 months ≈ 10 and 12 months ≈ 15. Enter your kitten’s age in weeks or months for its human equivalent and what is usually happening developmentally.
Right now: Weaning is complete or nearly so. This is the classic age for kittens to go to their new homes — they are eating solid food, using a litter box, and learning cat manners from play.
Kitten development, month by month
Kittens change faster in their first six months than at any other time in their lives, which is why kitten ages are quoted in weeks early on. The milestones below are the usual, commonly described pattern — individual kittens vary, and a kitten who is behind on several of them is worth a vet visit.
- Weeks 1–2 (≈ up to 6 human months): Born with eyes closed and ears folded. Eyes open around days 7–14; the kitten cannot regulate its own body temperature and depends entirely on its mother.
- Weeks 3–4 (≈ 1 human year): First wobbly walking, first teeth, and the start of exploring. Weaning usually begins around week 4.
- Weeks 5–8 (≈ 2 human years): Running, pouncing and litter-box training. This is the prime socialisation window — gentle handling and new sounds pay off for life. By 8 weeks most kittens are fully weaned and ready for a new home.
- Months 3–4 (≈ 4–6 human years): Coordination sharpens, adult eye colour settles in, and play gets serious. First vaccination courses typically happen in this window — your vet sets the schedule.
- Months 5–6 (≈ 8–10 human years): Approaching sexual maturity. Spay/neuter timing is usually decided around now, often at 5–6 months, before the first heat.
- Months 7–12 (≈ 11–15 human years): The Junior stage: nearly full-grown, energetic, and testing every boundary in the house. Growth plates close and adult weight settles towards the first birthday.
Need an older cat instead? The main cat age calculator takes years and months, and the full age chart covers 1 month to 25 years.
Common questions
How can I tell a kitten’s age if I don’t know it?
Vets estimate from teeth and weight: baby teeth are all in by about 6–8 weeks, adult teeth replace them between about 3 and 6 months, and a rough rule is about 1 pound (0.45 kg) of weight per month of age in the early months. An in-person vet estimate beats any rule of thumb.
How old is a 3-month-old kitten in human years?
About 4, on the veterinary life-stage chart — a weaned, litter-trained preschooler equivalent who is learning fast.
When does a kitten become a cat?
The Kitten life stage ends around 6 months; 7 months to 2 years is Junior. Most cats are close to adult size by 12 months, though some larger breeds keep filling out into their second year.