BMI, which stands for Body Mass Index, is a measure of one's weight against one's height. It is found by dividing an individual's weight in metric by the square of their height in metric units.
BMI is a health index that, as of 2015, is in wide use by doctors in the United States. BMI is often used as a way of determining if an individual is overly fat, although this usage is not always very accurate. For example, athletes with large amounts of muscle may be found to have an "obese" BMI, because muscle is very heavy and dense. However, for the general population, BMI is considered a reliable indicator of obesity, as it is strongly correlated with metabolic problems associated with being overweight.