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 with height 1.75 m:
BMI = 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 directly measure body fat. It may overestimate body fat in athletes and underestimate it in older people with lost muscle mass.

Q2: What is a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy. However, optimal BMI may vary by age, sex, and ethnicity.

Q3: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles rather than adult categories.

Q4: How often should I check my BMI?
A: Periodic checks (e.g., every 6-12 months) can help track changes, but focus more on overall health and lifestyle.

Q5: What are alternatives to BMI?
A: Waist circumference, waist-to-hip ratio, and body fat percentage measurements may provide additional information.