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 that may lead to health problems.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in pounds (lb)
• \( height \) — Height in inches (in)
• \( 703 \) — Conversion factor (kg/m²)/(lb/in²)

Explanation: The formula calculates body mass per unit of height squared, providing a standardized measure of body weight relative to height.

3. Importance of BMI Calculation

Details: BMI is a simple, inexpensive screening method for weight category—underweight, healthy weight, overweight, and obesity. While it doesn't measure body fat directly, research has shown BMI correlates with direct measures of body fat.

4. Using the Calculator

Tips: Enter weight in pounds and height in inches. For most accurate results, measure weight without heavy clothing and height without shoes. 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), 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: How often should I check my BMI?
A: For most adults, checking BMI annually is sufficient unless undergoing significant weight changes.

Q4: What's a healthy BMI range?
A: For most adults, 18.5 to 24.9 is considered healthy, though optimal range may vary by age and ethnicity.

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