In physiology and medicine, the Body Surface Area (BSA) is the measured or calculated surface of a human body. For many clinical purposes BSA is a better indicator of metabolic mass than body weight because it is less affected by abnormal adipose mass. Estimation of BSA is simpler than many measures of volume. 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). BMI has been used by the World Health Organization as the standard for recording obesity statistics since the early 1980s. BMI is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems. Simple convenient user interface.