How much should a kitten weigh? Month by month
By Pawculations Team · Cats · Updated
Summary: A healthy kitten gains roughly a pound per month for the first six months: about 1 lb at 4 weeks, 2 lb at 8 weeks, 4 lb at 4 months, 6 lb at 6 months. Newborns start at 3 to 5 ounces and should gain steadily every week. A kitten who stops gaining, or loses weight, needs a vet promptly; in young kittens that’s always urgent.
You’re holding a kitten and a kitchen scale, wondering if this tiny thing is on track. Here is the month-by-month math, how to weigh a wriggler accurately, and the red flags that shouldn’t wait.
Not sure of the age in the first place? The kitten age chart works it out from weight, teeth, and eyes together.
In this article
Kitten weight chart by age
| Age | Typical weight |
|---|---|
| Newborn | 3–5 oz (85–140 g) |
| 1 week | ~8 oz (225 g) |
| 3 weeks | ~15 oz (425 g) |
| 1 month | ~1 lb (450 g) |
| 2 months | ~2 lb (900 g) |
| 3 months | ~3 lb (1.4 kg) |
| 4 months | ~4 lb (1.8 kg) |
| 5 months | ~5 lb (2.3 kg) |
| 6 months | ~6 lb (2.7 kg) |
| 12 months | adult weight, most cats 8–12 lb |
Individual kittens spread around every number here: litter size, nutrition, and breed all matter, and a Maine Coon kitten will embarrass this chart by month four. The trend matters more than any single weigh-in.
The pound-a-month rule
For the first six months, age in months ≈ weight in pounds. It’s the rule shelters run on, and it’s why “2 pounds” doubles as shorthand for “8 weeks old and big enough to neuter.” Growth tapers after month six; most cats land at their adult weight around the first birthday. Underneath the rule sits steady weekly gain: young kittens should add weight every single week, roughly a quarter pound per week through the middle months.
How to weigh a kitten
A kitchen scale beats a bathroom scale by a mile at kitten sizes. Put a bowl or open box on the scale, hit tare, add kitten, read grams. Weigh at the same time of day (before a meal is most consistent), and write it down; a weight log is the cheapest health monitor a kitten can have. For very young fosters, daily weigh-ins are standard practice, and a gain of about 10 grams a day is the newborn benchmark.
When to worry
Weight is the earliest warning system kittens have. Call your vet promptly if a kitten loses weight at any age, gains nothing across a week, or falls badly behind littermates. In kittens under 8 weeks, treat weight loss as urgent the same day; tiny bodies have no reserves, and fading kittens go downhill fast. Chunky is a problem for later; in kittenhood, steady gain is the whole game.
FAQ
How much should a 4-month-old kitten weigh? About 4 pounds (1.8 kg), per the pound-a-month rule. Anywhere from 3.5 to 5 pounds is unremarkable, especially across breeds.
How much should an 8-week-old kitten weigh? About 2 pounds (900 g). That’s also the common shelter threshold for spay and neuter surgery.
When do kittens stop growing? Growth tapers from about 6 months, and most cats reach adult weight around 12 months. Large breeds like Maine Coons keep filling out for two years or more.
Is my kitten underweight? Compare against the chart, then watch the trend for a week. Below the range but gaining steadily is usually fine; on the range but not gaining is the real worry. Ribs you can see (rather than just feel) mean a vet visit either way.
Working out age and weight at the same time? The kitten age chart reads weight, teeth, and eyes together to place a kitten within about a week.
Sources
* This article draws on published veterinary sources, but it's for education and curiosity, not veterinary advice. Every pet is different; talk to your vet about what's right for yours.
