CDC growth chart calculator
Calculate BMI-for-age, weight-for-age and stature-for-age percentiles with exact age and transparent calculation steps.
Compared with children of the same age and sex in the CDC reference.
Standing height compared with the CDC stature-for-age reference.
Extended BMI method used: The BMI result exceeded the older chart’s 95th percentile, so the tool used CDC’s extended BMI calculation for the displayed BMI percentile and z-score.
Screening result—not a diagnosis: A percentile is one part of a child’s growth assessment. A healthcare professional should review accurate measurements, growth over time, health history and other relevant factors. Do not use this result to start or change treatment.
What this CDC growth chart calculator shows
The tool compares a child’s BMI, weight and standing height with the CDC 2000 sex- and age-specific reference data. It reports a percentile and z-score for each measure and explains every calculation step.
For higher BMI values, it applies the CDC 2022 extended BMI method rather than extending the original curve beyond the range where it performs well.
How CDC growth percentiles are calculated
Calculate exact age
The number of days between birth and measurement is divided by 30.4375 to obtain age in months.
age in months = elapsed days ÷ 30.4375Calculate BMI
Weight and height are converted to kilograms and metres before BMI is calculated.
BMI = kg ÷ height in metres²Interpolate L, M and S
The tool linearly interpolates the official CDC L, M and S reference values for exact age and the selected sex chart.
z = ((value ÷ M)^L − 1) ÷ (L × S)Convert z-score to percentile
The standard normal distribution converts the z-score to a percentile. High BMI uses CDC’s extended method.
percentile = normal CDF(z) × 100Example: a child measured at age 10
Suppose a female child born on April 15, 2016 is measured on September 28, 2026 at 140 cm and 36 kg. Select Female, enter both dates and measurements, then calculate.
- 1Calculate exact age from both datesExact age is used rather than age rounded to the nearest birthday.
- 236 ÷ 1.40² = 18.37 kg/m²This is the calculated BMI before age-specific interpretation.
- 3Interpolate each CDC reference curveBMI, weight and stature each use their own L, M and S values.
- 4Review the result in contextA clinician considers measurement accuracy and the pattern across visits—not one percentile alone.
How to interpret a growth chart result
A percentile describes position within a reference distribution. For example, the 60th percentile means the measurement is higher than about 60% of the reference group and lower than about 40%. It does not mean “60% healthy” or provide a diagnosis.
Repeated accurate measurements plotted over time are generally more informative than a single point.
Shoes, heavy clothing, posture, scale calibration or a typing error can materially change the result.
CDC recommends WHO growth standards from birth to age 2 and CDC charts from age 2 onward in the United States.
Prematurity, medical conditions and some genetic conditions can affect which chart and interpretation are appropriate.
How to measure height and weight
Standing height
Remove shoes and bulky hair accessories. Stand straight on a level floor with feet flat and look forward. Record to the precision supported by the measuring equipment.
Weight
Use a firm, level surface and a calibrated scale. Remove shoes and heavy outer clothing. Enter height and weight from the same measurement date.
CDC data and guidance used by this calculator
CDC growth chart calculator FAQs
What age range does this CDC growth chart calculator cover?
It covers exact ages from 24 months to under 240 months, which means ages 2 through 19. CDC recommends WHO growth standards for children younger than 2 years in the United States.
Which CDC percentiles does the tool calculate?
It calculates BMI-for-age, weight-for-age and stature-for-age percentiles and z-scores using the selected male or female CDC reference data.
How is exact age calculated?
The tool finds the elapsed days between the date of birth and measurement date, then divides by 30.4375 to calculate age in months for the CDC reference lookup.
What is a growth percentile?
A percentile describes where a measurement lies within the sex- and age-specific reference distribution. It is not a health score and cannot diagnose a condition.
What is a z-score?
A z-score describes distance from the reference median in standard-deviation units after applying the CDC LMS transformation. Zero is the reference median.
How is child BMI calculated?
BMI is weight in kilograms divided by height in metres squared. For children and teens, the value is then interpreted by age and sex using BMI-for-age percentiles.
What BMI categories does the calculator show?
It shows CDC screening categories: underweight below the 5th percentile, healthy weight from the 5th to below the 85th, overweight from the 85th to below the 95th, and obesity at or above the 95th percentile.
What is the CDC extended BMI method?
The extended method improves percentile and z-score calculation for very high BMI values where the original CDC 2000 BMI curve has limitations. The tool applies the method automatically when required by the CDC calculation program.
Does one percentile diagnose a growth or weight problem?
No. CDC describes growth charts and BMI as screening tools. A healthcare professional considers measurement accuracy, the trend over time, health history and other clinical information.
Why might a result differ from a clinic chart?
Differences can result from measurement technique, date or unit entry, rounding, the chart or method used, or corrected-age and condition-specific considerations. Confirm the inputs and ask the clinic which reference was used.
Can I use this calculator for a child born prematurely?
Ask a pediatric healthcare professional. Corrected age and the appropriate chart depend on age and clinical context; this general calculator does not make those decisions.
Are the dates and measurements stored?
No. The calculation runs in the browser, and this plugin does not transmit or store the values entered into the calculator.