Teen BMI Calculator (Ages 2–19)
Instant pediatric Body Mass Index calculation with US imperial units by default. Enter age, gender, weight, and height to see your CDC growth chart percentile category update in real time.
How This Calculator Works
Type the child's age, gender, weight, and height into the fields above. The calculator recalculates instantly with every keystroke — there is no "Calculate" button. The raw BMI value and approximate CDC percentile category update in real time.
BMI Formula (US Imperial)
For imperial units, BMI is computed as:
BMI = 703 × weightlb / heightin²
The constant 703 converts pound-per-square-inch into the standard kilogram-per-square-meter scale used by WHO and CDC.
CDC 2000 Growth Chart Percentile Lookup
Unlike adult BMI which uses fixed cut-points, teen BMI maps the raw BMI value onto age-specific and gender-specific percentile curves from the CDC 2000 Growth Charts. This tool uses published LMS (Box-Cox Cole-Green) reference data at whole-year intervals to provide approximate percentile category ranges. For exact percentile determination, LMS parameters must be interpolated to the child's exact age in months.
CDC Teen BMI Percentile Classification
| Category | Percentile Range | Color |
|---|---|---|
| Underweight | Below 5th percentile | Orange |
| Healthy weight | 5th – 84th percentile | Green |
| Overweight | 85th – 94th percentile | Yellow |
| Obese | 95th percentile and above | Red |
These categories are adopted by the CDC and American Academy of Pediatrics for pediatric BMI screening. The percentile cut-points at 5, 85, and 95 are screening conventions selected for consistency with expert committee recommendations.
Approximate CDC Percentile Reference Values
The table below shows approximate BMI values at the 5th, 85th, and 95th percentiles for selected ages, drawn from published CDC LMS data. These reference values illustrate how classification boundaries shift with age and gender.
| Age (yrs) | 5th % BMI | 85th % BMI | 95th % BMI | |||
|---|---|---|---|---|---|---|
| Female | Male | Female | Male | Female | Male | |
| 2 | 14.7 | 14.8 | 17.6 | 17.6 | 18.8 | 18.7 |
| 5 | 13.7 | 13.8 | 17.5 | 17.4 | 19.1 | 18.9 |
| 8 | 13.9 | 14.0 | 18.8 | 18.7 | 20.8 | 20.6 |
| 10 | 14.3 | 14.4 | 20.2 | 20.1 | 22.6 | 22.4 |
| 12 | 15.0 | 15.2 | 21.8 | 21.8 | 24.8 | 24.6 |
| 14 | 15.9 | 16.2 | 23.5 | 23.6 | 27.1 | 27.1 |
| 16 | 16.8 | 17.3 | 25.0 | 25.1 | 29.1 | 29.4 |
| 18 | 17.5 | 18.1 | 26.3 | 26.5 | 30.8 | 31.2 |
| 19 | 17.9 | 18.5 | 26.8 | 27.0 | 31.5 | 32.0 |
Interpreting Your Teen BMI Result
Teen BMI is a population-level screening tool, not a diagnostic test. The percentile rank indicates how the child's BMI compares to the CDC 2000 reference population of same-age, same-gender children. BMI values near any boundary should be treated as occupying a continuous distribution rather than as a binary categorical assignment. For clinical assessment and diagnosis, consult a qualified healthcare provider who can interpret BMI alongside growth patterns, body composition, and other clinical factors.