Check if your kitten is growing on schedule. Healthy kittens follow a remarkably consistent growth curve — and weight is the single best indicator of kitten health, especially in the first 8 weeks.
Editorially ReviewedThis compares your kitten's weight to the average for their age. Some natural variation is normal — breed, sex, and individual differences all play a role. Steady weekly gain matters more than hitting exact numbers.
Growth milestones, feeding guides, and seasonal reminders — one email a week.
Week-by-week developmental milestones.
Full reference chart 0-52 weeks.
Warning signs and when to call your vet.
More calculators for cat owners.
Kitten weight is the single most reliable indicator of health in the first 8 weeks of life. Unlike adult cats, who can mask illness for days or weeks, kittens show problems first in their growth curve. A kitten who stops gaining weight — even for a day or two in the first month — is showing you something is wrong before any other symptoms appear.
Our tracker compares your kitten's current weight to the expected range for their age, based on averaged growth data for domestic shorthair cats. Pedigree breeds vary — Maine Coons, Ragdolls, and Norwegian Forest Cats run significantly larger; Singapuras and Cornish Rex run smaller.
| Age | Average Weight (grams) | Average Weight (oz / lb) | Daily Gain (target) |
|---|---|---|---|
| Newborn (0 weeks) | 90-110 g | 3-4 oz | — |
| 1 week | 150-200 g | 5-7 oz | 10-15 g/day |
| 2 weeks | 225-275 g | 8-10 oz | 10-15 g/day |
| 3 weeks | 300-400 g | 10-14 oz | 10-15 g/day |
| 4 weeks | 400-500 g | 14-18 oz / ~1 lb | 10-15 g/day |
| 6 weeks | 650-750 g | 1.4-1.6 lb | 10-15 g/day |
| 8 weeks | 850-1000 g | ~2 lb | 10-15 g/day |
| 12 weeks | 1300-1400 g | 2.8-3.1 lb | ~15 g/day |
| 16 weeks (4 mo) | 1700-1900 g | 3.7-4.2 lb | — |
| 6 months | 2700-3100 g | 6-7 lb | — |
| 9 months | 3300-3700 g | 7-8 lb | — |
| 12 months | 3800-4400 g | 8-10 lb | — |
Beyond weight, certain developmental milestones tell you whether a kitten is on track. Use these to estimate age if you've taken in an orphan with no known birth date:
Weighing frequency depends on age:
The most important thing is consistency. Same scale, same time of day (ideally before feeding), and a written log or app where you can spot trends. A single low or high reading isn't meaningful; a pattern is.
For newborn through 8-week-old kittens, the following are veterinary emergencies:
If you're raising an orphan or motherless kitten, weight tracking becomes even more critical. Without a mother to provide constant care, you're responsible for monitoring every aspect of growth. Some additional guidance:
Newborn kittens weigh 3-5 oz (85-140 g). By 1 week they're 5-8 oz. By 4 weeks they should weigh about 1 lb (450 g). By 8 weeks they're typically 2 lb. By 6 months most kittens weigh 5-6 lb.
By 12 months, most cats reach their adult weight of 8-12 lb. Breed plays a big role — Maine Coons and Ragdolls grow much larger and longer than average.
Newborn kittens should be weighed daily for the first 2 weeks — they should gain about 10-15 grams per day. From weeks 2-8, weigh weekly to confirm steady growth.
After 8 weeks, weighing every 1-2 weeks is enough until 6 months, then monthly until adult weight. Consistent weight gain is one of the most important indicators of kitten health.
A kitten that isn't gaining weight is a veterinary emergency, especially in the first 4 weeks. Possible causes include inadequate nutrition (mother not producing enough milk, weak suckling), parasites (very common — most kittens have worms), infection, congenital problems, or temperature regulation issues.
Get to a vet within 24 hours. Kittens have very small energy reserves and can decline rapidly.
Healthy growing kittens shouldn't be 'overweight' in the way adult cats are — they need calories to fuel rapid growth. However, kittens can be overfed in ways that set them up for adult obesity.
Free-feeding kibble, lots of treats, and lack of play time can establish patterns that lead to weight problems by age 1-2. Stick to measured meals 3-4 times per day for kittens under 6 months, then 2-3 times per day.
Most domestic shorthair and mixed-breed cats reach their adult weight around 12 months of age, though they may continue to fill out and develop muscle until 18 months.
Large breeds like Maine Coons, Norwegian Forest Cats, and Ragdolls don't reach full size until 3-4 years of age and can weigh 12-20 pounds at maturity. Spaying or neutering doesn't significantly affect adult size, just sexual development.
If you've taken in a kitten without a known birth date, you can estimate age from several markers: eyes open at 7-10 days; eye color changes from blue to adult color around 6-7 weeks; weaning around 4-5 weeks; deciduous (baby) teeth come in around 3-6 weeks; adult teeth start replacing them at 3-4 months.
Weight is a useful additional data point — see our chart above. A vet can give the most accurate estimate.