Typical kitten weight by age
The classic guideline breeders and shelters use: a kitten weighs about 100 grams at birth and gains roughly 100 grams per week — 10 to 15 grams a day — through the first months. Individual kittens vary with breed, litter size and sex, so a band of about ±20% around the line is normal. The direction of change matters more than any single number: a healthy kitten gains steadily every week.
| Age | Typical weight | Milestones |
|---|---|---|
| 1 week | ~150–250 g | Eyes still closed, sleeps and nurses |
| 4 weeks | ~350–550 g | Walking, first teeth, starting to explore |
| 8 weeks | ~750–1050 g | Fully weaned, first vaccinations |
| 12 weeks | ~1150–1550 g | Typical adoption age, very playful |
| 16 weeks | ~1550–2050 g | Adult teeth coming in |
| 24 weeks | ~2300–3100 g | Growth begins to taper; spay/neuter window |
When slow gain is an emergency
In kittens under 8 weeks, weight is a vital sign. Any weight loss — or 24–48 hours without gain — in a kitten under 8 weeks warrants an immediate call to a vet. Tiny kittens have almost no fat or glycogen reserves; a kitten that stops nursing can slide into hypoglycemia, dehydration and hypothermia in hours, a spiral known as fading kitten syndrome. Weigh young kittens daily at the same time, on a kitchen or baby scale, and write it down — the trend line is the earliest warning you will get.
The growth taper after 6 months
The 100 g/week rule only holds for roughly the first 24 weeks. After 6 months, growth slows markedly: most cats reach about 80% of adult size by then and finish growing at 10–12 months, while large breeds such as Maine Coons continue filling out for 2–4 years. This is also when calorie needs drop — keep feeding kitten food until about 12 months, but switch from eat-to-appetite to measured portions as the curve flattens, or the growth chart quietly turns into a weight chart.
Frequently asked questions
How much should a kitten weigh at each age?
A useful rule of thumb: kittens weigh about 100 grams at birth and gain roughly 100 grams per week, so an 8-week kitten typically weighs around 900 grams (about 2 lb). Healthy kittens vary by around 20% either side of that line, and breed and litter size shift it too.
How fast should a kitten gain weight?
Roughly 10-15 grams per day (about 100 grams per week) through the first few months. Daily weighing at the same time each day, on a kitchen or baby scale, is the most reliable way to track a young kitten.
My kitten is losing weight — is that an emergency?
In a kitten under 8 weeks old, yes. Any weight loss, or failure to gain over 24-48 hours, in a very young kitten warrants an immediate call to a veterinarian — small kittens have no reserves and can crash from hypoglycemia and dehydration within hours.
When do kittens stop growing?
Growth is fastest in the first 4-5 months, tapers noticeably after 6 months, and most cats reach adult weight around 10-12 months. Large breeds like Maine Coons keep filling out until 2-4 years old.