In the Anagen phase in a normal scalp, most follicles are growing (90-95%). Anagen is the active growth phase of hair follicles. The cells in the root of the hair are dividing rapidly, adding to the hair shaft. During this phase the hair grows about 1 cm every 28 days. Scalp hair stays in this active phase of growth for 2-7 years. The amount of time the hair follicle stays in the Anagen phase is genetically determined and is shorter for men with male pattern baldness.