1. What is BMI?

Definition: Body Mass Index (BMI) is a measure of body fat based on your weight in relation to your height.

Purpose: It provides a simple numeric measure to help categorize a person as underweight, normal weight, overweight, or obese.

2. How Does the BMI Calculator Work?

The calculator uses the formula:

Where:

• \( BMI \) — Body Mass Index (kg/m²)
• \( W \) — Weight (kilograms)
• \( H \) — Height (meters)

Explanation: Your weight in kilograms is divided by the square of your height in meters.

3. BMI Categories (UK Standard)

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5 to 24.9
• Overweight: BMI 25 to 29.9
• Obese: BMI 30 or greater

4. Using the Calculator

Tips: Enter your weight in kilograms and height in meters. All values must be > 0.

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 not be accurate for athletes with high muscle mass or elderly with lost muscle mass.

Q2: What's the difference between UK and US BMI?
A: The calculation is identical, but some classification systems may vary slightly between countries.

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

Q4: How often should I check my BMI?
A: For most adults, checking every few months is sufficient unless you're actively trying to change your weight.

Q5: What if my BMI is in the overweight or obese range?
A: Consult with a healthcare professional for personalized advice about diet and exercise.