WHO baby percentile calculator
Enter your baby's sex, date of birth, and a measurement to see where it falls on the WHO Child Growth Standards. It works for weight, length, and head circumference from birth to 24 months.
Everything is calculated in your browser. Nothing you enter is sent or stored.
Fill in both dates and at least one measurement to see the percentile.
How the calculator works
The calculator uses the WHO Child Growth Standards (2006), which are based on 8,440 healthy breastfed children in Brazil, Ghana, India, Norway, Oman, and the USA. For each age and sex, WHO publishes three values (L, M, and S) that describe the curve. Your measurement is turned into a z-score with the LMS formula, and the z-score into a percentile.
Ages between whole months are interpolated. Length means length measured lying down, the standard method until age 2.
The BabyTrack+ app uses the same tables and the same calculation in its growth tab, so the numbers match.
Common questions
What percentile is normal for a baby?
There is no single normal percentile. A baby on the 10th percentile can be as healthy as one on the 90th. What doctors watch is whether your baby keeps roughly following the same curve over time. Crossing two centile lines, up or down, is worth discussing.
Is this the same chart my pediatrician uses?
In the US, the CDC recommends the WHO charts for children under 2. The UK uses the UK-WHO charts, built on the same WHO data but drawn with more centile lines. Other countries may use their own charts, so the percentile can differ slightly.
Why is my result different from the clinic's?
Different scales, clothing or a full diaper, and a wriggly baby on the length board all change the result a little. Measurements a few weeks apart tell you more than any single one.
Track growth over time
BabyTrack+ plots every measurement on the WHO curves and keeps the history on your phone, offline. Free for one baby.