I found a pretty good site which will calculate the body surface area automatically for you. The site is: http://medicine.ucsd.edu/cystinosis/bodysurf.htm In addition to the body surface area, you will also need to determine a dosing constant for your child. This number could be anywhere from 15mg/m2 to 30mg/m2, depending on the severity of your child's CAH manifested block. The surface area (in meters) multiplied by your child's dosing constant will give you the total daily medication (cortisone) in grams. It is worthwhile to perform blood work on your child to check the Androstenedione and Testosterone levels. Bone age xrays are also helpful. The dosing constant is revised, depending on the results of the blood work and bone age xrays. Important feedback about dosing levels can be provided by the physical size and weight of your child. Try to get a growth chart to plot height and weight versus time. If your child is growing too fast, you may be giving too little hydrocortisone. If you child is growing too slowly, you may be giving too much hydrocortisone. Good luck to you and your family!