Growth chart guide
CDC vs WHO Growth Charts: Which One Should You Use?
In the usual U.S. workflow: WHO before age 2, CDC from age 2. At the switch, check the chart, how the measurement was taken, and which number is being compared.
This guide is educational and does not replace advice from your child’s healthcare professional.
The short answer
Under 2: WHO
Use the WHO Child Growth Standards. Length is measured lying down (recumbent length). Weight-for-length compares weight with babies of the same sex who have that lying-down length.
Age 2+: CDC
Use the CDC growth charts for children and adolescents. Measure standing height. When height and weight are available, BMI-for-age compares weight relative to height with children of the same age and sex.
Why a percentile or classification may change after the switch
Three things can change together around age 2:
- WHO chart → CDC chart: a different comparison group.
- Lying-down length → standing height: a different measurement method.
- Weight-for-length → BMI-for-age: a different way to compare weight and size.
A percentile change at the switch does not, by itself, prove that the child suddenly changed biologically. Check the measurement, chart, and indicator before comparing the last WHO point with the first CDC point.
To learn how to follow chart axes and curves after the transition, read How to Read a CDC Growth Chart. For the distinct meanings of the under-2 indicators, read What Do Baby Growth Percentiles Mean?.
Why the U.S. workflow switches at age 2
CDC recommends the WHO Child Growth Standards from birth to age 2 and the CDC 2000 growth charts from age 2 through adolescence. The boundary creates a consistent U.S. workflow; it does not mean the WHO standards themselves stop at age 2, because WHO publishes standards through age 5.
Other countries and clinical systems may follow a different chart policy. Follow the chart used in your child’s record; preterm birth or a specialized clinical context can require a different approach.
WHO is a growth standard; CDC is a growth reference
The WHO standards describe how children grew under health, nutrition, and environmental conditions selected for the WHO Multicentre Growth Reference Study. CDC describes them as a growth standard.
The CDC 2000 charts describe how children in historical U.S. samples grew. CDC therefore calls them a growth reference. Neither chart is a scorecard, and the 50th percentile is not a target that every child should reach.
The measurement changes from recumbent length to standing height
Before age 2, length is measured with the child lying down. From age 2, stature is generally measured standing. CDC notes that standing height is about 0.8 cm less than recumbent length on average, so changing methods can contribute to a visible shift at the transition.
Child Growth Lab does not automatically convert one measurement method into the other. Do not enter unadjusted standing height in a recumbent-length field or unadjusted recumbent length in a standing-height field. The appropriate method and any adjustment belong to the applicable clinical protocol.
The weight comparison changes from weight-for-length to BMI-for-age
In the under-2 workflow, WHO weight-for-length compares weight with children of the same sex at the same recumbent length. It does not use age as the numerical comparison coordinate and is not infant BMI.
From age 2, CDC BMI-for-age relates weight to standing height and then compares BMI by age and sex. The calculation and screening categories answer a different question from weight-for-length. For focused BMI screening detail, use the Kids BMI Calculator.
Choose the calculator that matches the record
Birth to before age 2
Use the Baby Growth Calculator for WHO weight-, recumbent-length-, weight-for-length-, and head-circumference-for-age references.
Ages 2 through 19
Use the Child Growth Chart Calculator for CDC height-, weight-, and—when both are entered—BMI-for-age results.
Preterm context
The calculators do not select a preterm chart or decide whether corrected age applies. Start with the purpose-specific corrected-age guide.
When to ask about the chart choice
- Ask your child’s healthcare professional if you are unsure which chart, age basis, or measurement method applies.
- Bring earlier records if a carefully repeated measurement still looks very different after the switch.
- Discuss ongoing changes or concerns about feeding, growth, development, or symptoms rather than judging one point alone.
This comparison helps with chart selection; it does not diagnose a cause or recommend treatment.
Frequently asked questions
When do U.S. growth charts switch from WHO to CDC?
CDC recommends WHO growth standards from birth to age 2 and CDC growth charts from age 2 onward in the United States. The applicable chart and clinical workflow can differ in other countries or for an individual child.
Why can a percentile change at the second birthday?
The chart population, measurement method, and plotted indicator can change together. Recumbent length usually changes to standing height, and weight-for-length changes to BMI-for-age. A different percentile after the transition does not by itself show a sudden biological change.
Should BMI-for-age be used before age 2?
CDC does not recommend BMI-for-age interpretation for children younger than 2 years. The usual under-2 workflow uses WHO weight-for-length when both weight and recumbent length are available.
Does the age-2 switch apply the same way to a child born preterm?
Not necessarily. Preterm growth assessment can require a different chart and corrected-age approach. The chart, age basis, and duration of correction depend on the purpose and clinical context; Child Growth Lab calculators do not select those automatically. What Is Corrected Age for Premature Babies?