BMI Calculation and Interpretation: Categories from Underweight to Class III Obesity

Formula

BMI = Weight (kg) / [Height (m)]²

Example

75 kg / (1.75)² = 75 / 3.0625 = 24.5 (Normal)

Categories

• Underweight <18.5
• Normal 18.5–24.9
• Overweight 25–29.9
• Obese I 30–34.9
• Obese II 35–39.9
• Obese III ≥40

Context

Interpretation varies by age, sex, ethnicity, and athletic status. Use with clinical judgment.