What is the correct BMI formula and the standard category ranges?

• A. BMI = height / weight; Underweight 12-16; Normal 17-21; Overweight >25; Obesity >40
• B. BMI = weight (lb) / height (in)^2 * 703; categories not defined
• C. BMI = weight (kg) * height (m)^2; categories reversed
• D. BMI = weight (kg) / [height (m)]^2; Underweight <18.5; Normal 18.5–24.9; Overweight 25–29.9; Obesity ≥30

Answer: (D)

BMI estimates body fat by comparing weight to a squared height, so the standard calculation uses weight in kilograms divided by the square of height in meters: BMI = weight (kg) / [height (m)]^2. If you measure in pounds and inches, you can still use BMI by applying the conversion factor: BMI = [weight (lb) / (height (in))^2] × 703. The commonly used category thresholds are underweight less than 18.5; normal weight 18.5–24.9; overweight 25–29.9; and obesity at 30 or greater. This option matches both the correct formula and these widely accepted cut points, making it the best choice. Other formulas either mix up weight and height, omit the unit conversion, or lack the defined category ranges, which is why they aren’t correct.