The body mass index (BMI) is a measure that uses your height and weight to determine if your weight is healthy. BMI is calculated by dividing an adults weight in kilograms by their height in meters squared. For most adults, an ideal BMI is in the 18.5 to 24.9 range. If your BMI is below 18.5, youre in the underweight range; between 18.5 and 24.9, youre in the healthy weight range; between 25 and 29.9, youre in the overweight range; and 30 or over, youre in the obese range. Its important to note that BMI is a screening measure and is not intended to diagnose disease or illness. At an individual level, BMI can be used as a screening tool but is not diagnostic of the body fatness or health of an individual. A trained healthcare provider should perform appropriate health assessments to evaluate an individuals health status and risks.