What is BMI?
Body Mass Index is a simple measure that uses your height and weight to estimate whether you're in a healthy weight range. It's calculated as your weight in kilograms divided by the square of your height in metres (or 703 × pounds ÷ inches² in imperial units).
What BMI does and doesn't tell you
BMI is a useful general guide for populations, but it has limits for individuals. It doesn't distinguish muscle from fat, so very muscular people may have a high BMI while still being healthy. Use it as a starting point, not a diagnosis.