BMI for Teens Calculator — Age & Sex Adjusted
Unlike adult BMI, teen BMI is interpreted against age- and sex-specific CDC percentile charts. Enter your child's age, sex, and measurements to see their BMI and which percentile band they fall in.
Sex
years
Units
kg
cm
Age- and sex-adjusted CDC percentile category shown below
- 1
Height in metres
1.6 - 2
Height squared (m²)
1.6 × 1.6 = 2.56 - 3
BMI
55 ÷ 2.56 = 21.5Weight (kg) divided by height squared (m²).
How does this calculator work?
Teen BMI = weight (kg) ÷ height (m)² — the same formula as adults, but the category is determined by age- and sex-specific CDC percentile cut-offs: below the 5th percentile is underweight, 5th–85th is healthy, 85th–95th is overweight, and ≥95th is obese. The exact BMI boundaries shift with age and sex.
Formula
How this is calculated
Body Mass Index is calculated the same way for all ages — weight in kilograms divided by height in metres squared. What changes for children and teenagers is how the number is interpreted. Because body fat naturally changes as children grow, and because boys and girls develop at different rates, a single BMI number means different things depending on age and sex.
The CDC uses growth-chart data collected in 2000 to define four categories based on percentile rank: below the 5th percentile is underweight, the 5th to below the 85th is healthy weight, the 85th to below the 95th is overweight, and the 95th or above is obese. This calculator interpolates the BMI cut-off values for the 5th, 85th, and 95th percentiles at the entered age and sex from those CDC reference tables, then places the calculated BMI into the corresponding band.
The percentile cut-offs embedded here are approximate interpolated values. They reflect the CDC 2000 reference data but should not be used for clinical decisions. For an exact percentile result, use the CDC's official BMI Percentile Calculator for Children and Teens or consult a paediatrician. BMI is a screening indicator only — it does not directly measure body fat or assess health comprehensively.
Frequently asked questions
The formula (weight ÷ height²) is the same, but the categories differ. Children's body fat changes as they grow and varies between boys and girls, so the same BMI number has a different meaning at age 10 vs. age 17. The CDC uses percentile charts from large population samples rather than fixed cut-offs to define healthy weight ranges for ages 2–20.
For teens, "healthy weight" means BMI between the 5th and 85th percentile for the same age and sex. The exact BMI that corresponds to those percentiles changes with age — for example, a 14-year-old boy's healthy range is roughly BMI 15.3–20.7, while at 17 it is about 16.8–22.6.
BMI is a useful screening tool but has limitations for teens as well as adults: it does not distinguish muscle from fat, and some teens (especially athletes or those going through growth spurts) may fall into a category that does not reflect their actual body composition. A doctor combines BMI percentile with growth trends, diet history, and physical examination for a complete assessment.
Also known as
TG we-Calculate Editorial Team. (2026). BMI for Teens Calculator — Age & Sex Adjusted [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bmi-teens-calculator
TG we-Calculate Editorial Team. "BMI for Teens Calculator — Age & Sex Adjusted." TG we-Calculate. 2026. https://we-calculate.com/calculator/bmi-teens-calculator.
TG we-Calculate Editorial Team, "BMI for Teens Calculator — Age & Sex Adjusted," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bmi-teens-calculator
@misc{wecalculate_bmi_teens_calculator, title = {BMI for Teens Calculator — Age & Sex Adjusted}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bmi-teens-calculator}}, year = {2026}, note = {TG we-Calculate} }
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