Teen BMI & Healthy Weight Calculator (Ages 13-19)
Accurate BMI calculator for teenagers that uses percentile-based growth charts rather than adult standards. Supports healthy development during puberty.
About
Adolescence is a period of rapid and volatile growth. A 14-year-old boy who has hit his growth spurt will have a completely different body composition than a 14-year-old who hasn't. Because of this, standard adult BMI calculators are inappropriate and misleading for teenagers.
This tool evaluates weight in the context of age and gender-specific percentiles, derived from extensive growth data (CDC/WHO). Instead of a simple "Normal/Overweight" label, it places the teenager on a curve relative to peers, providing a more accurate picture of development. It emphasizes that "Healthy" is a wide range during these formative years.
Formulas
Teen BMI is calculated typically, but interpreted via percentile ranking:
The percentile (P) is determined by comparing the BMI Z-score against age-specific distribution data:
Where L, M, and S are age/sex-specific parameters from the growth chart database.
Reference Data
| Percentile Range | Weight Status Category | Action Step |
|---|---|---|
| Below 5th Percentile | Underweight | Consult a pediatrician to rule out nutritional deficits. |
| 5th - 85th Percentile | Healthy Weight | Maintain healthy eating and activity habits. |
| 85th - 95th Percentile | Overweight | Focus on slowing weight gain while height increases. |
| Above 95th Percentile | Obesity | Professional medical advice recommended for metabolic health. |