1. What is BMI?

Body Mass Index (BMI) is a measure of body fat based on height and weight that applies to adults and children. For children, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How is BMI Calculated?

The calculator uses the standard BMI formula:

Where:

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

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

3. Understanding BMI Percentiles

Details: For children, BMI is plotted on growth charts to obtain a percentile ranking. Percentiles are the most commonly used indicator to assess size and growth patterns in children.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, age in years, and select gender. All values must be valid (weight > 0, height > 0, age between 0-20).

5. Frequently Asked Questions (FAQ)

Q1: What do BMI percentiles mean for children?
A: Underweight (<5th), Healthy weight (5th-85th), Overweight (85th-95th), Obese (≥95th).

Q2: Why use percentiles for children?
A: Children's body composition varies by age and sex, so BMI must be compared against growth charts.

Q3: How accurate is BMI?
A: BMI correlates with body fat but doesn't directly measure it. Athletes may have high BMI due to muscle.

Q4: When should BMI be measured?
A: Pediatricians typically measure BMI at all well-child visits starting at age 2.

Q5: Are there limitations to BMI?
A: BMI doesn't account for muscle mass, bone density, or fat distribution. It's a screening tool, not diagnostic.