1. What is BMI?

Body Mass Index (BMI) is a value derived from the mass and height of a person. For children, BMI is interpreted using age- and sex-specific percentiles rather than the standard categories used for adults.

2. How Does the Calculator Work?

The calculator uses the BMI formula:

Where:

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

Explanation: The BMI calculation provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

3. Importance of BMI Calculation

Details: BMI is an inexpensive and easy-to-perform method of screening for weight category, such as underweight, normal or healthy weight, overweight, and obesity. For children, BMI percentiles are the most commonly used indicator to assess the size and growth patterns of individual children.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. All values must be valid (weight > 0, height > 0). For female children, the result should be interpreted using CDC growth charts for girls.

5. Frequently Asked Questions (FAQ)

Q1: Why is BMI different for children than adults?
A: Children's body composition varies as they grow and differs between boys and girls. Therefore, BMI for children is age- and sex-specific.

Q2: What are the BMI percentile categories for children?
A: Underweight (<5th percentile), Healthy weight (5th to <85th percentile), Overweight (85th to <95th percentile), Obese (≥95th percentile).

Q3: How often should a child's BMI be calculated?
A: BMI should be calculated at least annually as part of routine health supervision visits.

Q4: Are there limitations to BMI for children?
A: BMI doesn't directly measure body fat and can be influenced by factors like muscle mass, bone density, and puberty stage.

Q5: Where can I find growth charts to interpret my child's BMI?
A: The CDC provides growth charts for girls aged 2-20 years at https://www.cdc.gov/growthcharts/.