The ANAGEN PHASE (growth) lasts between 2 and 7 years. It varies significantly between men and women, lasting only up to 4 years in men, up to 7 in women.

During the anagen phase, the cells inside the hair follicle slowly form the hair, which grows at around 1 centimetre per month in men and 1.5 centimetres per month in women. Because hair growth is also determined by genetic factors, the actual rate of growth varies from one individual to another.

The CATAGEN PHASE sees the hair growth functions gradually slowing and stopping over a period of about two weeks on average. The catagen phase serves the essential purpose of preventing hair from growing indefinitely. During this phase, the bulb rises towards the surface of the skin in preparation for the next phase.

The TELOGEN PHASE is a phase of inactivity and generally lasts some 3-4 months.
By the end of the telogen phase all growth functions have ceased for some time and the old hair simply falls out. The follicle then enters another anagen phase.
About 90% of human hair is in an active growth phase at any one time.
The growth cycles of your individual hairs are therefore distributed in such a way that hair is never all lost at the same time (as occurs in the moulting of some animals).

The average human scalp has around 100,000 follicles, and a daily hair loss of up to 100 hairs is absolutely normal.