Infant Growth Percentile Tracker
Track your baby growth percentile based on age, weight, and length.
Uses simplified WHO growth chart data for boys and girls.
Your data stays in your browser. We do not store, collect, or transmit any information you enter.
Growth Percentile Estimate
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
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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