A mathematical way of looking at the coverage of hair.
By Jae Pak, M.D. This is a calculator to find how many grafts or hairs you need to cover your bald area. An average Caucasian male is born with 100,000 hairs with each hair diameter of 0.06 mm. The average area of your scalp is 1,000 square millimeters. This is about the size of one and a half of a regular paper. The average cross-sectional area of 100,000 hairs is less than the size of a postage stamp. This means most of the area on your scalp surface is empty (with no hair)! You need at least 1/2 inch of hair length to cover your scalp with hair.