BSAcalc is the freeware program for the calculation of the Surface Area of the Body. The distinctive feature of BSAcalc is that it has a large selection of formulas for the calculation. These latest updates to the BSAcalc include calculation the Body Mass Index (BMI). BMI is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. BMI is defined as the weight in kilograms divided by the square of the height in meters (kg/m2).