BMI Calculator for Kids & Teens
Use this tool to calculate raw BMI for children aged 2–19. Compare the result with BMI-for-age percentile charts for an accurate interpretation.
Results
BMI
19.4
Reminder
Compare this BMI with CDC or WHO BMI-for-age percentile charts for girls aged 10.
Converted values: Height 140.0 cm • Weight 38.0 kg
How to Use This Calculator
Measure consistently
Record height without shoes and weight with light clothing. Use the same scale and time of day for repeat measurements.
Enter age and sex
BMI interpretation for children depends on age- and sex-specific percentiles, so provide accurate information.
Review the percentile charts
Use the BMI result with CDC (US) or WHO (global) percentile charts to determine whether the child is underweight, healthy weight, overweight, or obese.
Formula
BMI = Weight ÷ Height²
- Metric: weight (kg) ÷ height² (m²)
- Imperial: weight (lb) ÷ height² (in²) × 703
- Convert BMI to a percentile using age- and sex-specific charts.
Understanding BMI-for-Age
For children and adolescents, BMI must be interpreted using growth charts that reflect age and sex. Percentiles classify weight status: underweight (<5th percentile), healthy weight (5th–85th percentile), overweight (85th–95th percentile), and obesity (≥95th percentile).
Use official CDC or WHO charts, or consult your pediatric healthcare provider for accurate interpretation and next steps.
Frequently Asked Questions
How do I find the BMI percentile?
Use CDC BMI-for-age percentile charts (US) or WHO growth standards. Locate the child’s age on the x-axis and plot the BMI on the chart.
How often should I measure my child’s BMI?
Annual well-child visits are typical. More frequent monitoring may be recommended if the child is outside the healthy percentile range.
Do BMI percentiles differ for boys and girls?
Yes. Growth patterns differ by sex, so separate charts are required for accurate classification.
What if my child’s BMI percentile is high?
Discuss the result with a pediatric healthcare provider. They can evaluate lifestyle, family history, and growth trends before recommending action.