1. What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = 703 × weight (lb) / [height (in)]². It provides a reliable indicator of body fatness for most people and is used to screen for weight categories.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula for American measurements:

Where:

• \( weight \) — Weight in pounds (lb)
• \( height \) — Height in inches (in)
• 703 — Conversion factor for American units

Explanation: The equation calculates body mass relative to height squared, providing a standardized measure of body composition.

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 identify possible weight problems in adults.

4. Using the Calculator

Tips: Enter weight in pounds and height in inches. All values must be valid (weight > 0, height > 0). For most accurate results, measure height without shoes and weight with minimal clothing.

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 (BMI ≥ 30).

Q2: Is BMI accurate for everyone?
A: BMI may overestimate body fat in athletes and underestimate it in older people who have lost muscle mass.

Q3: Why use 703 in the formula?
A: 703 is the conversion factor needed when using pounds and inches (kg/m² × (2.2046 lb/kg) × (39.37 in/m)² ≈ 703).

Q4: What's 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.

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