BMI Calculator

Body Mass Index (BMI) is calculated by dividing your weight in kilograms by the square of your height in meters (kg/m²). The resulting number is then placed into one of four standard WHO categories: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25.0–29.9), and Obese (30.0 and above). The formula was developed in the 1830s by Belgian mathematician Adolphe Quetelet and has been used by the WHO and CDC as a population-level screening tool. It is not a clinical diagnostic — it is a quick, cost-free first indicator.

BMI has known limitations that are important to understand. It does not distinguish between muscle mass and fat mass, which is why elite athletes often test as "overweight" or even "obese" despite very low body fat percentages. It does not account for where fat is distributed in the body (abdominal fat carries higher cardiovascular risk than peripheral fat). Studies also show BMI cutoffs may not apply equally across different ethnic groups. For individual health assessment, BMI is best used as one data point among others — alongside waist circumference, blood pressure, cholesterol levels, and a healthcare professional's evaluation. This tool supports both metric (kg/cm) and imperial (lb/in) units.