THE REFERENCE LIBRARY
A little clarity, at every age.
Explore the measurements, understand the comparisons, and calculate with your baby’s exact dates.
Popular calculators
Infant percentile calculatorDiaper size calculator by brandAverage newborn and birth weightBaby and child growth calculator
Infant and baby weight percentile calculator
Infant and baby weight percentile calculatorAverage newborn weight and weight percentiles1-month-old baby weight percentiles2-month-old baby weight percentiles3-month-old baby weight percentiles4-month-old baby weight percentiles6-month-old baby weight percentile8-month-old baby weight percentiles9-month-old baby weight percentiles12-month-old baby weight percentiles15-month-old baby weight percentiles18-month-old baby weight percentiles24-month-old baby weight percentilesChild weight percentile calculator: ages 2–18
Baby length percentile calculator
Baby length percentile calculatorNewborn length percentiles1-month-old baby length percentiles2-month-old baby length percentiles3-month-old baby length percentiles4-month-old baby length percentiles6-month-old baby length percentiles8-month-old baby length percentiles9-month-old baby length percentiles12-month-old baby length percentiles15-month-old baby length percentiles18-month-old baby length percentiles24-month-old baby length percentilesChild height percentile calculator: ages 2–18
Baby head circumference percentile calculator
Baby head circumference percentile calculatorNewborn head circumference percentiles1-month-old baby head circumference percentiles2-month-old baby head circumference percentiles3-month-old baby head circumference percentiles4-month-old baby head circumference percentiles6-month-old baby head circumference percentiles8-month-old baby head circumference percentiles9-month-old baby head circumference percentiles12-month-old baby head circumference percentiles15-month-old baby head circumference percentiles18-month-old baby head circumference percentiles24-month-old baby head circumference percentiles
MOST USEFUL CALCULATORS & GUIDES
Start with the question you need answered.
Weight-for-length calculatorInfant weight in proportion to recumbent length.Child BMI percentileCDC BMI-for-age from age 2 through 18.Extended BMI percentileCDC 2022 method for high BMI values.Growth trackerSave and chart dated measurements locally.Print, export and backupKeep a readable or restorable copy.Infant percentile calculatorWeight, length and head circumference by exact age.Diaper size comparisonCompare six manufacturer weight charts.Baby weight percentile guideUnderstand weight-for-age and its limits.Newborn weight referenceWHO birth medians and percentile table.6-month weight referenceWHO values plus exact-date guidance.
Review status: Maintained by Baby Growth and technically reviewed on 29 September 2026. Calculations and product ranges are checked against the cited WHO, CDC and manufacturer sources. This independent tool has not received clinical review and does not replace professional care.