What Is BMI (Body Mass Index)?
Body Mass Index (BMI) is a widely used screening tool that measures body fat based on your height and weight. It provides a simple numeric indicator of whether you're at a healthy weight for your height.
BMI Formula
Metric: BMI = weight (kg) ÷ height² (m²)
Imperial: BMI = 703 × weight (lbs) ÷ height² (inches²)
BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Moderate |
| 18.5 – 24.9 | Normal weight | Low |
| 25.0 – 29.9 | Overweight | Increased |
| 30.0 – 34.9 | Obese (Class I) | High |
| 35.0 – 39.9 | Obese (Class II) | Very High |
| 40.0+ | Obese (Class III) | Extremely High |
Limitations of BMI
BMI doesn't account for muscle mass, bone density, or body composition. Athletes with high muscle mass may register as "overweight" despite being healthy. For a more complete picture, consider waist circumference and body fat percentage alongside BMI.