Infant Growth Percentile Tracker
Track baby growth percentiles for weight and length from birth to 24 months.
Plots your baby on the WHO curve for boys and girls, metric or imperial.
Infant growth percentiles compare your baby’s size to other babies of the same age and sex. They are based on the WHO (World Health Organization) growth standards.
What percentiles mean:
- 50th percentile = Average (half of babies are larger, half are smaller)
- 25th percentile = Smaller than 75% of babies that age
- 75th percentile = Larger than 75% of babies that age
- 3rd–97th percentile = Normal range
Typical growth milestones:
| Age | Boys Weight | Girls Weight | Boys Length | Girls Length |
|---|---|---|---|---|
| Birth | 3.3 kg (7.3 lbs) | 3.2 kg (7.1 lbs) | 49.9 cm (19.6 in) | 49.1 cm (19.3 in) |
| 3 months | 6.4 kg (14.1 lbs) | 5.8 kg (12.8 lbs) | 61.4 cm (24.2 in) | 59.8 cm (23.5 in) |
| 6 months | 7.9 kg (17.4 lbs) | 7.3 kg (16.1 lbs) | 67.6 cm (26.6 in) | 65.7 cm (25.9 in) |
| 12 months | 9.6 kg (21.2 lbs) | 8.9 kg (19.6 lbs) | 75.7 cm (29.8 in) | 74.0 cm (29.1 in) |
| 24 months | 12.2 kg (26.9 lbs) | 11.5 kg (25.4 lbs) | 87.8 cm (34.6 in) | 86.4 cm (34.0 in) |
Important notes:
- Consistent growth along ANY percentile curve is healthy
- A sudden jump or drop in percentile may warrant discussion with your pediatrician
- Breastfed and formula-fed babies may grow at slightly different rates
- Premature babies should use adjusted age for the first 2 years, so subtract the weeks they arrived early from their calendar age before entering it
Range: this covers birth to 24 months, which is where the WHO standards use recumbent length. From 2 years the charts switch to standing height and a different reference, so the numbers here stop rather than being stretched to cover ages they were never built for.
A note on the method: real WHO charts are built from a skewed distribution, and this page approximates them with a symmetric one around the published median. Near the middle the two agree closely. Out at the 3rd and 97th percentiles the estimate drifts by a few points, so treat an extreme reading here as a prompt to check the real chart at your next appointment, not as a measurement.
Units: 1 kg = 2.205 lbs | 1 cm = 0.394 inches
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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