The hair growth period of a hair follicle is called the anagen stage. The anagen stage for follicles located on our scalp typically lasts between about 3-5 years.
All hairs grow at roughly the same rate.
The length of the anagen stage of a follicle can be measured by the length of the hair it produces. Some people have follicles which on average stay in the anagen stage for far more than 5 years. These people can grow very long hairs. Certain hair follicles, such as eyelash follicles and the follicles for hair on your arms, have a growth stage lasting only a month or two, and as a result the hairs they produce usually do not grow very long. The transition to the resting period is called the catagen stage.