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. It is defined as a person's weight in kilograms divided by the square of their height in meters.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

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

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. Importance of BMI Calculation

Details: BMI is a simple, inexpensive, and non-invasive surrogate measure of body fat. While not a direct measure of body fat, BMI correlates moderately well with more direct measures of body fat. It is used to screen for weight categories that may lead to health problems.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and age in years. All values must be valid (weight > 0, height > 0, age ≥18 as this is for adults).

5. Frequently Asked Questions (FAQ)

Q1: What are the standard BMI categories?
A: Underweight (BMI < 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), and Obese (≥30).

Q2: Is BMI accurate for everyone?
A: BMI may overestimate body fat in athletes and those with muscular builds, and underestimate body fat in older persons who have lost muscle mass.

Q3: How often should I check my BMI?
A: For most adults, checking BMI annually is sufficient unless you're actively trying to lose or gain weight.

Q4: Does BMI change with age?
A: While the BMI formula doesn't change with age, the interpretation might for older adults as body composition changes.

Q5: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI percentiles rather than the adult categories.