Body mass index, usually called body mass index, is a simple index to judge whether the weight is healthy or not. Its calculation formula is the weight in kilograms divided by the square of height in meters (kg/m2).
For example, an adult female has a height of 1.56m, a weight of 50kg and a body mass index of 50 ÷1.56 ÷1.56 = 20.5.