1. What is BMI?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, normal weight, overweight and obesity in 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 more objectively with their patients.

3. Understanding BMI Percentiles

Details: For children and teens, BMI is age and sex-specific and is often referred to as BMI-for-age. 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, height in meters, age in years, and select gender. All values must be valid (weight > 0, height > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: What is a healthy BMI range?
A: For adults, 18.5-24.9 is normal. For children, the healthy range varies by age and sex and is best determined using percentiles.

Q2: How are percentiles determined?
A: Percentiles compare a child's BMI to others of the same age and gender from reference growth charts.

Q3: What percentile indicates overweight?
A: Generally, ≥85th percentile is overweight and ≥95th is obese, but consult a healthcare provider for individual assessment.

Q4: Are there limitations to BMI?
A: BMI doesn't distinguish between muscle and fat, so athletes may have high BMI without excess fat. It also doesn't account for fat distribution.

Q5: Should BMI be used alone for diagnosis?
A: No, BMI is a screening tool. Other assessments like skinfold thickness, diet, activity, and family history should be considered.