1. What is BMI?

Body Mass Index (BMI) is a person's weight in kilograms divided by the square of height in meters. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How BMI is Calculated

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms
• \( height \) — Height in meters

Note: For children and teens, the BMI number is plotted on the CDC BMI-for-age growth charts to determine a percentile ranking.

3. Importance of BMI for Teens

Details: BMI-for-age is the most widely used indicator to screen for weight categories that may lead to health problems in children and teens.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For most accurate results, measure height without shoes and weight in light clothing.

5. Frequently Asked Questions (FAQ)

Q1: How is BMI different for children than adults?
A: For children and teens, BMI is age- and sex-specific and is interpreted using percentile rankings rather than fixed categories.

Q2: What do the percentile rankings mean?
A: Underweight (<5th percentile), Healthy weight (5th to <85th percentile), Overweight (85th to <95th percentile), Obese (≥95th percentile).

Q3: Why use BMI if it doesn't measure body fat directly?
A: BMI is a simple, non-invasive screening tool that correlates well with more direct measures of body fatness in most children.

Q4: When should I be concerned about my child's BMI?
A: Consult a healthcare provider if your child's BMI is below the 5th percentile or at or above the 85th percentile.

Q5: Where can I find CDC growth charts?
A: CDC growth charts are available at https://www.cdc.gov/growthcharts/clinical_charts.htm