Use our free bmi calculator online to get accurate, personalized results. Calculate your Body Mass Index based on height and weight.
Body Mass Index (BMI) is a widely used screening tool that estimates body fat based on your height and weight. It was developed by Belgian mathematician Adolphe Quetelet in the early 19th century and remains one of the most accessible ways to assess whether you fall within a healthy weight range.
BMI is calculated by dividing your weight in kilograms by your height in meters squared (kg/m²). The resulting number falls into one of four categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25–29.9), and obese (30 and above).
While BMI is a useful starting point, it does not directly measure body fat. Athletes with high muscle mass may have elevated BMI scores despite being healthy. Similarly, older adults may have a normal BMI but carry excess fat. For a more comprehensive assessment, consider combining BMI with waist circumference measurements, body fat percentage tests, or other health markers.
Research has shown strong correlations between high BMI values and increased risk of heart disease, type 2 diabetes, high blood pressure, and certain cancers. Maintaining a BMI within the normal range is associated with lower risk of these chronic conditions and better overall health outcomes. Regular monitoring of your BMI can help you track changes over time and take proactive steps toward maintaining a healthy weight.