1. What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in meters squared. BMI provides a reliable indicator of body fatness for most people.

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 is calculated by dividing weight in kilograms by the square of height in meters. The result is categorized into standard ranges.

3. Importance of BMI Calculation

Details: BMI is a simple, inexpensive screening tool for weight categories that may lead to health problems. It's used to screen for weight categories that may lead to health problems but is not diagnostic of body fatness or health.

4. Using the Calculator

Tips: Enter weight in kilograms, height in meters, and optionally age. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: What are the 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 it in older persons who have lost muscle mass.

Q3: Why include age in the calculator?
A: While age doesn't affect BMI calculation, it helps provide more context for interpreting results as healthy BMI ranges may vary slightly with age.

Q4: What are limitations of BMI?
A: BMI doesn't directly measure body fat and doesn't account for muscle mass, bone density, overall body composition, or racial and sex differences.

Q5: Should children use this calculator?
A: Children and teens need age- and sex-specific percentiles rather than the adult categories shown here.