The time period of hair growth, specifically the active growth phase (anagen), typically lasts between 2 to 8 years.
During this anagen phase, hair grows at an average rate of about 1 centimeter (approximately 0.4 inches) every 28 days. This growth rate can be influenced by various factors, including genetics, age, health, and diet. This active growth period determines the potential length of the hair. After the anagen phase, hair enters the catagen (transition) and telogen (resting) phases before eventually shedding and restarting the cycle.
