Growing children’s BMI must be compared with an age- and sex-specific reference. This calculator uses US CDC growth charts; it does not report a Korean percentile.
The calculator code is being prepared.
How to use: a worked example
Select Boy, enter 5 completed years and 0 additional months, height 110cm and weight 19kg, then calculate. The result is BMI 15.7, approximately the 59.3rd percentile, in the CDC healthy weight range. This is a demonstration, not an assessment of a real child.
Enter age and measurements accurately
For 5 years and 6 months, enter years 5 and additional months 6. Date mode requires both birth date and measurement date. When a month lacks the birth day, its final day counts as the monthly anniversary. Completed age n months uses the n+0.5 monthly data row without interpolation.
Measure standing height without shoes and choose cm, m or in. Choose kg or lb for weight. This tool does not automatically correct age for prematurity or convert recumbent length. Incorrect units can change the result substantially.
BMI versus BMI-for-age percentile
BMI is weight in kilograms divided by height in meters squared. A percentile describes its position among the reference group of the same age and sex. It is not height percentile or a health probability. For height and weight considered separately, use the growth percentile calculator.
CDC screening categories
| Category | Reference |
|---|---|
| Underweight | Below the 5th percentile |
| Healthy weight | 5th to below the 85th |
| Overweight | 85th to below the 95th |
| Obesity | At or above the 95th |
| Severe obesity | At least 120% of the 95th percentile BMI, or BMI at least 35 |
Categories use unrounded values. “120% of the 95th percentile” is not a 120th percentile. Screening categories do not establish a diagnosis or treatment plan.
Does this replace the Korean growth reference?
No. Reference populations and growth charts differ. For evaluation in Korea, consult the official KDCA growth calculator and a clinician. This tool does not redistribute the Korean 2017 chart values.
Next steps and visit preparation
Growth history, puberty, eating, activity, sleep, conditions and medicines provide essential context. Seek clinical assessment for rapid weight changes, slowing growth or accompanying symptoms. Avoid weight stigma or a weight-loss target based on this calculator alone.
Health records library · Symptom timeline and visit questions · Lab result guide · Health calculators
Save a result summary as PDF
After calculation, use Preview result summary or Print / save as PDF below the result. Selecting the blank log adds a separate page. The summary includes original measurements, units, age, reference and results. Share sends only the page address, without entered measurements.
Methods and limitations
Through the 95th percentile, the tool uses CDC 2000 LMS transformation and a normal cumulative distribution. Above it, the 2022 extension uses 90+10Φ((BMI−P95)/sigma). Extreme percentiles display as <0.1 or >99.99. Consistent growth records are more informative than one measurement.
- CDC: extended BMI data and formulas
- CDC: child and teen BMI categories
- CDC: official BMI calculator and limitations
Sources checked by Life Choice Note: 2026-09-30. General health information without separate medical-professional review; not a substitute for diagnosis or treatment.