Teen BMI Percentile Calculator
Calculate BMI percentile for teenagers aged 13-19.
Uses CDC growth charts to determine healthy weight status by age and gender.
BMI for teenagers (ages 2–19) is calculated using the same formula as adult BMI, but the interpretation is fundamentally different. Instead of fixed cutoffs, teen BMI is evaluated using age- and sex-specific percentiles from CDC growth charts, because body composition naturally changes with age and differs between boys and girls during puberty.
BMI formula (same as adults): BMI = Weight (kg) ÷ Height (m)²
Or in imperial units: BMI = (Weight (lbs) ÷ Height (inches)²) × 703
Teen BMI interpretation — percentile-based:
- Below 5th percentile: Underweight
- 5th to < 85th percentile: Healthy weight
- 85th to < 95th percentile: Overweight
- 95th percentile and above: Obese
Where:
- Percentile — compares the child’s BMI to other children of the same age and sex in the CDC reference population
- Age — must be used as a third variable (unlike adult BMI which only uses weight and height)
- Sex — boys and girls have different BMI-for-age charts due to different body composition patterns during puberty
Why adult BMI cutoffs don’t apply to teens: A 14-year-old boy with a BMI of 22 is in the healthy range. The same BMI of 22 in a 10-year-old boy would be at the 95th percentile — classified as obese. Context is everything.
Worked example: 14-year-old girl. Weight: 130 lbs (59.1 kg). Height: 5'3" (160 cm = 1.60 m).
- BMI = 59.1 ÷ (1.60)² = 59.1 ÷ 2.56 = 23.1
- Using CDC BMI-for-age chart for 14-year-old girls: BMI 23.1 falls at approximately the 80th percentile
- Interpretation: Healthy weight (between 5th and 85th percentile)
The same BMI of 23.1 in an adult would also be classified as healthy, but for a 10-year-old girl it would be above the 95th percentile (obese). Always use age- and sex-specific charts for anyone under 20.