Baby Growth Percentile Calculator
Where does your baby's weight or length fall on the official CDC growth charts (birth to 24 months)? Real LMS tables, the documented CDC formula.
Data: CDC / National Center for Health Statistics growth charts (the WHO-derived birth-to-24-month charts), using the CDC's documented LMS method — z = ((value/M)L − 1)/(L·S), percentile from the standard normal distribution. Half-month age points are interpolated linearly, exactly as the tables are designed to be used.
Reading percentiles without the panic
A percentile places your baby among peers of the same age and sex — it is a comparison, not a score. A baby on the 12th percentile who follows their own curve is typically perfectly healthy; what pediatricians watch is the trend. Measurements taken at home (especially length) also carry wobble, so treat single points gently.
Questions people ask
Why 0-24 months only?
That is the range of the WHO-derived CDC infant charts this tool uses, and it covers the period pediatricians measure most densely. From age 2, CDC's standing-height charts take over — we may add them, but not with approximated data.
Head circumference?
Not yet — we only publish measures whose complete official tables we could source and verify end-to-end. Weight-for-age and length-for-age meet that bar today.