Calculate your Body Mass Index (BMI) with our free online BMI calculator. Get instant results and understand your weight category with helpful health insights.
BMI, or Body Mass Index, is a measure developed by Adolphe Quetelet in the 1830s to assess body weight relative to height. It’s calculated as weight (kg) divided by height (m) squared: BMI = weight / (height * height).
While widely used, BMI has limitations—it doesn’t distinguish between muscle and fat, making it less accurate for athletes. Still, it’s a quick health screening tool endorsed by the World Health Organization (WHO).
Your BMI falls into categories: Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), and Obese (≥30). Each category suggests different health risks or needs.
For example, Underweight may indicate malnutrition—consult a doctor if persistent. Overweight or Obese categories suggest risks like diabetes or heart disease, encouraging lifestyle changes like balanced diets and exercise.
Example 1: Weight 65kg, Height 170cm: BMI = 65 / (1.7 * 1.7) = 22.5 (Normal).
Example 2: Weight 90kg, Height 180cm: BMI = 90 / (1.8 * 1.8) = 27.8 (Overweight).
Example 3: Weight 50kg, Height 160cm: BMI = 50 / (1.6 * 1.6) = 19.5 (Normal).