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Free Baby Growth Percentile Calculator — WHO Chart

Calculate baby weight, length, and head circumference percentiles using WHO Child Growth Standards. Enter age, sex, and measurements for instant, clear results.

mo
kg
cm
cm
Results
Weight
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Length
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Head
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Based on the WHO Child Growth Standards (0–24 months) using the LMS method (Lambda / Mu / Sigma) to compute a z-score, converted to percentile via the standard normal distribution. Prototype uses approximate LMS values — verified WHO reference tables will replace these before launch.
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What this percentile means

A percentile compares your baby to other babies of the same age and sex. The 60th percentile for weight means 60% of babies that age and sex weigh less, and 40% weigh more.

There is no "best" percentile. A healthy baby can sit anywhere on the chart. What pediatricians watch for is the trend over time, not a single reading.

If a baby moves sharply across percentile bands between visits, that's worth a conversation with your provider — high or low.

How to use this calculator

  1. 01Pick your baby's sex and your preferred units.
  2. 02Enter age in months. Use half-months (e.g. 6.5) for more precision.
  3. 03Enter at least one measurement — weight, length, or head circumference.
  4. 04Percentiles update as you type. No button to press.

Common questions

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