BMI stands for Body Mass Index, a parameter adopted by the World Health Organization to calculate the ideal weight of each person.The index is calculated as follows: the patients weight is divided by his height squared. The individual is said to have normal weight when the BMI result is between 18.5 and 24.9.Want to find out your BMI? Enter your weight and height in the fields below and compare with the indexes in the table. Important: Follow the examples and use periods as separators.