BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in metres: BMI = kg / m². For imperial units the equivalent formula is BMI = 703 × lb / in². The result is a dimensionless number used as a quick screening indicator of body weight relative to height.
The standard WHO BMI ranges are: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), and Obese (30 and above). These are population-level screening thresholds, not a clinical diagnosis. BMI does not account for muscle mass, bone density, age, or sex. Always consult a healthcare professional for a complete health assessment.