Growth Chart Calculator
Calculate weight, height, head circumference, and BMI percentiles using WHO 2006 and CDC 2000 standards for children ages 0–20 years
lbs
oz
ft
in
Use recumbent length (lying down) for infants under 2 years; standing height for children 2 and older
inches
Measured around the widest part of the head. Used for infants aged 0–24 months.
Enter Child Measurements to Calculate
Select the child's sex, enter their age and measurements, then click Calculate Percentiles to see growth percentiles, Z-scores, and a visual chart.
How to Use the Growth Chart Calculator
Select Mode, Units, and Sex
Choose Growth Measurement mode to assess current percentiles, or Height Predictor mode to estimate adult height from parental heights. Select Imperial or Metric units, then choose Boy or Girl. The calculator will automatically apply WHO charts for ages 0–24 months and CDC charts for ages 2–20 years.
Enter Age and Measurements
Enter the child's age using either the Date of Birth method (most accurate — enter date of birth and today's measurement date) or manual years and months entry. Then enter weight and height/length. For infants under 2, optionally add head circumference. If the child was born premature (before 37 weeks), expand the Preterm Birth Adjustment section and enter gestational age to apply corrected age.
Click Calculate Percentiles
Press the Calculate Percentiles button to generate results instantly. The tool displays summary donut charts, color-coded percentile band bars for each metric, Z-scores, and — for children aged 2 and older — BMI weight status. For infants, head circumference percentile is also shown if entered. The data source badge (WHO or CDC) confirms which standard was applied.
Interpret Results and Export
Green markers on the percentile bars indicate values in the typical 10th–90th percentile range. Yellow indicates borderline ranges, and red indicates below the 5th or above the 95th percentile — ranges that may warrant discussion with a pediatrician, especially if they represent a change from previous measurements. Use the Export CSV button to save results for record-keeping, or Print Results to share with a healthcare provider.
Frequently Asked Questions
What does a growth percentile actually mean for my child?
A growth percentile tells you what percentage of children of the same age and sex your child is at or above. For example, a child at the 30th percentile for height is taller than 30 percent of peers — meaning 70 percent are taller. Importantly, any percentile from the 3rd to the 97th is considered within the normal range of human variation. What matters more than any single percentile number is consistency: a child who tracks steadily along the 15th percentile curve from birth is growing normally. Concern arises when a child drops significantly across percentile lines over several visits, which can signal nutritional issues, illness, or other factors affecting growth. Always discuss results with your pediatrician to put measurements in context with your child's full health history.
Why does the calculator switch from WHO to CDC charts at age 2?
The WHO 2006 Child Growth Standards were developed from a study of children raised in optimal conditions in six countries — breastfed, non-smoking households, good nutrition. These standards describe how children should grow and are recommended by the American Academy of Pediatrics for infants under 2 in the US. The CDC 2000 Growth Reference, by contrast, is based on nationally representative samples of US children and describes how children actually grew historically in the US population. The switch at 24 months reflects standard US clinical practice and the fact that WHO data collected at 2 years used recumbent length (lying), while CDC data used standing height — creating a small but real measurement difference that pediatricians account for at the transition. Some children appear to shift percentiles slightly at age 2, which is expected and not cause for concern.
My child was born prematurely. How does the preterm correction work?
Premature infants are often smaller than full-term babies of the same chronological age simply because they had less time to grow in the womb. Plotting a 4-month-old born at 32 weeks (8 weeks early) at their full 4-month chronological age on a growth chart would make them appear severely small compared to full-term 4-month-olds, when in fact they are growing appropriately for their actual developmental stage. The corrected age adjusts for this by subtracting weeks of prematurity from the chronological age. A 4-month-old born 8 weeks early has a corrected age of approximately 2 months — much more appropriate for growth chart comparison. This calculator applies corrected age automatically when you enter a gestational age below 37 weeks. Correction is typically applied until age 2 to 2.5 years in clinical practice, by which time most premature children have caught up to the growth charts of full-term peers.
What BMI percentile is considered overweight or obese for children?
Unlike adults, children's BMI classifications use age- and sex-specific percentile thresholds because a healthy BMI value changes as children grow and develop. The CDC defines four weight status categories for children aged 2–20: underweight is below the 5th percentile; healthy weight is the 5th to below the 85th percentile; overweight is the 85th to below the 95th percentile; and obesity is at or above the 95th percentile. A fifth category — severe obesity — was formally recognized by the CDC in 2022 for children with BMI at or above 120 percent of the 95th percentile for their age and sex, or BMI of 35 kg/m² or greater. This threshold identifies children at the highest risk who may benefit from more intensive clinical evaluation and support. Note that BMI is a screening tool, not a diagnosis — athletic children with high muscle mass may have elevated BMI percentiles that do not reflect excess body fat.
How accurate is the mid-parental height predictor?
The mid-parental height method (Tanner et al., 1970) is the simplest and most widely used clinical tool for predicting a child's genetic height potential. It calculates a target height from the average of both biological parents' heights, adjusted by 6.5 cm upward for boys or 6.5 cm downward for girls, reflecting the average height difference between men and women. The expected adult height range of target height plus or minus 8.5 cm represents approximately the 3rd to 97th percentile of possible outcomes — meaning 94 percent of children will fall within this range. The method's accuracy is moderate: it captures genetic potential well but cannot account for nutrition, chronic illness, hormonal factors, or other environmental influences. Children who fall significantly outside their mid-parental target range — especially those well below the lower end — may warrant evaluation for growth hormone deficiency or other conditions by a pediatric endocrinologist.
Should I be worried if my child is above the 95th percentile or below the 5th percentile?
Not necessarily — but values outside the 5th to 95th percentile range do warrant closer attention and discussion with your pediatrician. By definition, 10 percent of healthy children fall outside these boundaries (5 percent above, 5 percent below), so a single extreme reading is far more likely to reflect normal variation than a medical problem. Tall parents tend to have tall children; small parents tend to have smaller children. The key questions are: Is the child tracking consistently along the same curve over time, or have they dropped or risen across multiple percentile lines? Is the pattern consistent with the parents' own heights? Is there any concerning medical history, such as poor appetite, recurrent illness, or developmental delays? Weight-for-height or BMI percentile puts height and weight in context together. Consult your pediatrician at every well-child visit and bring your growth chart printouts for comparison to previous measurements.