About 90% of scalp hairs will be in the first stage, "anagen" or growing phase for as long as 4-5 years. The second stage is the resting or "catagen" stage which lasts only a few months and ends when the hair falls out as a result of new growth underneath .

The new growth occurs in the third stage, "telogen" phase which is one of intense cellular activity in the hair follicles, which are responsible for the production of new hairs.

Scalp hairs grow at an average rate of 1/2 to 1 inch per year. The normal average rate of loss can range from 50 to 100 hairs per day with just combing shampooing or just sitting still