Kitten Growth Chart
What should a kitten weigh at a given age? DiGangi et al. (2019) measured two groups of kittens up to 20 weeks and published the average weight and spread at each age. This chart shows exactly what they measured — nothing extrapolated beyond it.
Average weight for a kitten this age…
0.92 kg
about 2.0 lb — published range 0.78–1.06 kg (1.7–2.3 lb) for a 8-week-old kitten.
Every published weight, by week and by cohort
| Weeks | Cohort | Average | ± 1 SD | n |
|---|---|---|---|---|
| 0 | Neonatal (longitudinal) | 0.11 kg | 0.02 kg | — |
| 2 | Neonatal (longitudinal) | 0.3 kg | 0.05 kg | — |
| 4 | Neonatal (longitudinal) | 0.48 kg | 0.1 kg | — |
| 6 | Neonatal (longitudinal) | 0.66 kg | 0.12 kg | — |
| 8 | Neonatal (longitudinal) | 0.92 kg | 0.14 kg | — |
| 6 | Pediatric (cross-sectional) | 0.69 kg | 0.14 kg | 31 |
| 8 | Pediatric (cross-sectional) | 1.02 kg | 0.18 kg | 609 |
| 10 | Pediatric (cross-sectional) | 1.22 kg | 0.26 kg | 298 |
| 12 | Pediatric (cross-sectional) | 1.45 kg | 0.34 kg | 206 |
| 14 | Pediatric (cross-sectional) | 1.73 kg | 0.43 kg | 80 |
| 16 | Pediatric (cross-sectional) | 1.93 kg | 0.46 kg | 54 |
| 18 | Pediatric (cross-sectional) | 1.83 kg | 0.24 kg | 4 |
| 20 | Pediatric (cross-sectional) | 2.18 kg | 0.4 kg | 28 |
The two cohorts overlap but do not agree: at 8 weeks the neonatal cohort (followed over time) averages 0.92 kg, while the pediatric cohort (a single cross-sectional sample) averages 1.02 kg — about 10% apart, from two different populations of kittens. That is why this calculator switches from one cohort to the other at 8 weeks rather than blending them into a single number neither study published.
The 18-week row above is lower than the 16-week row before it — 1.83 kg against 1.93 kg. That is not an error: only 4 kittens were weighed at 18 weeks in that study, against 54 at 16. The row is kept exactly as published, with its sample size shown, rather than smoothed away.
At 2 weeks, the two published sources do not even agree with each other: DiGangi et al. give a mean of 300 g, while the ASPCA's own kitten weight chart publishes a ceiling of 295 g at the same age — a 1.7% gap between two respected sources measuring the same thing. Neither figure is wrong; it is a reminder that any single number here is an average from a study, not a guarantee for one kitten.
And past 10 weeks, weight stops being a reliable way to estimate age at all: the study's own accuracy within one week fell from 98.8% at two weeks to 17.9% at 20 weeks. This chart does not predict an adult cat's weight from any of these figures — no published study supports that.
Common questions
How much should my kitten weigh?
At 8 weeks a kitten averages 1.02 kg, and at 12 weeks about 1.45 kg, in a study of 609 kittens at that age. Individual kittens vary widely — the chart shows the spread, not a target.
Why does this chart stop at 20 weeks?
Because that is where the published data stops. DiGangi et al. measured kittens up to 20 weeks. Extending the curve past the measurements would be inventing numbers, so this chart ends where the study does.
Can I tell my kitten’s age from its weight?
Up to about 10 weeks, reasonably well. After that the authors found weight often over- or underestimates age: their accuracy within one week fell from 98.8% at two weeks to 17.9% at 20 weeks. Past 10 weeks, teeth and eye colour tell you more than the scale.
Will this tell me how big my cat will get?
No. This chart shows what kittens weigh while they are growing; it does not predict adult weight. No published study supports predicting an individual cat's adult weight from an early weight, so this site does not claim to.
My kitten is outside the range — is something wrong?
Not necessarily. The range shown is one standard deviation around the average, so a healthy kitten can sit outside it. What matters more is the direction of travel over several weighings. A kitten that stops gaining, or loses weight, should be seen by a veterinarian.
This chart does not predict your cat's adult weight, and it does not replace a veterinary exam. A kitten that stops gaining weight, or loses weight, should be seen by a veterinarian regardless of what this chart shows.
Verified on . Based on Assessment of body weight for age determination in kittens (DiGangi et al., Journal of Feline Medicine and Surgery, 2019 (tables 1 and 2, weight-for-age, male and female)) and Kitten Age & Weight Chart (ASPCA Pro, 2023 (golden-test source, not used to build the calculation)). See the method.