1. What is BMI?

Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in meters (kg/m²).

2. How BMI is Calculated?

The BMI formula is:

Where:

• Weight — Measured in kilograms (kg)
• Height — Measured in meters (m)

Example: For a person weighing 70 kg and 1.75 m tall: 70 ÷ (1.75 × 1.75) = 22.9 kg/m²

3. BMI Categories

WHO Classification:

• Underweight: BMI < 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obese: BMI ≥ 30

4. Using the Calculator

Instructions: Enter your weight in kilograms and height in meters. For height, you can convert from cm to m by dividing by 100 (e.g., 175 cm = 1.75 m).

5. Frequently Asked Questions (FAQ)

Q1: Is BMI accurate for everyone?
A: BMI is a useful screening tool but doesn't account for muscle mass, bone density, or fat distribution. Athletes may have high BMI without excess fat.

Q2: How does BMI differ for children?
A: Children's BMI is age and sex-specific, plotted on growth charts rather than using fixed thresholds.

Q3: What are the limitations of BMI?
A: Doesn't distinguish between fat and muscle, may misclassify muscular individuals as overweight/obese, and doesn't account for fat distribution.

Q4: Are there better measures than BMI?
A: Waist circumference, waist-to-hip ratio, or body fat percentage may provide additional information about health risks.

Q5: Should BMI thresholds vary by ethnicity?
A: Some populations (e.g., Asian) may have higher health risks at lower BMI thresholds, leading to different classification cutoffs.