Calculate height-for-age and weight-for-age percentiles for a boy or girl: enter age (or birth and measurement dates), sex, and height, weight or both. First choose the reference: this tool supports US CDC 2000 for ages 2 through 18, or Korean NHIS data for 0–84 completed months. A separate WHO growth-chart option is not available. Results include the selected reference, original measurements, an explanation and a printable summary.
The interactive calculator is awaiting code activation. The guide and official links below are available.
How to use the calculator
- Choose a reference and the sex used by that chart. The Korean and US references are separate.
- Enter birth and measurement dates, or age in months. Date fields use YYYY-MM-DD. Enter height, weight or both with their original units.
- Select standing height or recumbent length, then calculate. Read the reference and limits before interpreting the percentile.
- Preview the summary and choose Print / Save PDF. You may include a blank growth log.
Which reference should I choose?
| Reference | Supported age | Meaning |
|---|---|---|
| Korean NHIS public LMS data | 0–84 completed months | A limited infant/child dataset; it does not cover Korean adolescents. |
| US CDC 2000 | 24 to under 228 months (ages 2 through 18) | US reference data; a CDC percentile is not a Korean-chart percentile. |
For an older Korean child, use the official KDCA calculator linked above. This tool does not silently switch populations when a child reaches the age limit. Changing the reference must be deliberate; record that choice when comparing results.
What does a percentile mean?
A percentile compares one measurement with the chosen reference for sex and age. The 50th percentile is the median, not an ideal target. A position below the 3rd or above the 97th percentile calls for careful measurement and context, rather than an automatic diagnosis. A clinician can review the child’s pattern over time, family height and puberty.
Weight-for-age alone cannot diagnose obesity. This calculator does not apply adult BMI categories to children or provide a pediatric obesity diagnosis.
Age and measurement methods
NHIS uses completed calendar months without interpolation; when a birth day is absent from a later month, the anniversary is the last day of that month. CDC uses elapsed days divided by 30.4375 and a monthly midpoint row (for example, 48.5 covers 48 to under 49 months). The data row is printed with the result.
Below 24 months, NHIS uses recumbent length; standing height is adjusted by +0.7 cm. From 24 months, recumbent length is adjusted by −0.7 cm for NHIS or −0.8 cm for CDC. Original and adjusted values both appear in the summary. Choose the method actually used.
How is the percentile calculated?
L, M and S come from the selected age/sex row. For L ≠ 0, Z = [(X/M)L − 1]/(L × S); for L = 0, Z = ln(X/M)/S. The percentile is 100 × the standard normal cumulative probability at Z. The tool shows 3rd, 50th and 97th reference values, and bounds very small or large percentiles as <0.1 or >99.9.
Examples and limits
“Fill example” inserts the selected reference’s height and weight medians for a 60-month-old boy. Both give the 50th percentile. Measurements start blank; the example is not a prediction for your child. Preterm birth may require a different age or chart, which this tool does not choose automatically.
Frequently asked questions
Must I enter both height and weight?
No. Either measurement is sufficient. Enter both only if they were measured for the same assessment.
Does one percentile show growth rate?
No. Keep earlier dates and measurements and compare the series using the same reference.
Where does the PDF save?
Select “Save as PDF” in the browser’s print dialog. It saves on your device and includes the original values and reference. Nothing is emailed by this calculator.
Related resources
Health calculators · Health records and visit preparation · Symptom timeline and visit questions · Official Korean growth calculator (Korean)
Official data and sources
- NHIS: publicly available infant and child growth LMS data
- CDC: 2000 growth-chart LMS and percentile files
- KDCA: Korean child and adolescent growth charts
- CDC: age calculation and 0.8 cm position adjustment
- CDC/WHO: 0.7 cm infant position adjustment
- American Academy of Pediatrics: understanding growth charts and growth over time
Sources checked 2026-09-30 · General health information, not a substitute for care. No independent clinician review is claimed.