Baby Weight Percentile
Check your baby's weight and height percentile against WHO growth standards.
Based on WHO Child Growth Standards. Always consult a paediatrician for health assessments.
Understanding percentiles
A percentile shows how your baby compares to other babies of the same age and sex. The 50th percentile is the average. Being at the 25th or 75th percentile is completely normal.
| Percentile | Meaning | Classification |
|---|---|---|
| < 3rd | Below normal range | Underweight / Short |
| 3rd – 15th | Below average | Below average |
| 15th – 85th | Normal range | Normal |
| 85th – 97th | Above average | Above average |
| > 97th | Above normal range | Overweight / Tall |
Frequently asked questions
What are WHO growth standards?
The WHO Multicentre Growth Reference Study (MGRS) tracked healthy children in Brazil, Ghana, India, Norway, Oman, and the USA who were raised in optimal conditions. These charts represent how children should grow, not just how they do grow in a particular country.
My baby is at the 20th percentile. Should I be worried?
Not necessarily. Percentiles show relative size, not health. A consistent pattern matters more than a single measurement. If your baby tracks steadily along the 20th percentile over time, that's normal for them. Concern arises when there is a significant drop across percentile lines (e.g., from 50th to 10th) over a few months.
How accurate is this calculator?
This calculator uses WHO weight-for-age and height-for-age reference data with key percentile values at common age points. Results are interpolated between age points. For detailed clinical assessment, use the complete WHO charts or consult your paediatrician.
What is a Z-score?
A Z-score (standard deviation score) shows how many standard deviations your baby's measurement is from the median. Z-score of 0 = 50th percentile. Z-score of -2 = approximately 3rd percentile. Z-score of +2 = approximately 97th percentile. Values between -2 and +2 are considered within normal range.
Should I use weight-for-height instead?
Weight-for-height (or BMI-for-age) is useful for assessing proportionality — whether a baby is heavy for their length. This calculator provides weight-for-age and height-for-age. For a complete picture, your paediatrician will assess all three in combination.