Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It provides a rough estimate of body fatness and is used as a screening tool for weight categories — underweight, healthy weight, overweight, and obese.
BMI = weight (kg) / height² (m²) [Metric]
BMI = 703 × weight (lb) / height² (in²) [Imperial]
Weight in kilograms divided by height in meters squared (metric). For imperial units, multiply pounds by 703 then divide by height in inches squared.
Example 1: Person weighs 70 kg and is 1.75 m tall (metric)
Result: BMI = 22.86 (Healthy Weight: 18.5–24.9)
Example 2: Person weighs 180 lbs and is 5'10" (70 inches) tall (imperial)
Result: BMI = 25.83 (Overweight: 25.0–29.9)
Use our free BMI Calculator to skip the manual math.
Open BMI Calculator