Average human hair growth rate is approximately ½ inch or 1 cm a month. However hair follicles aren’t always in the growth stage: anagen – the growth stage takes 2-7 years in which human hair follicle grows hair. After that, a follicle enters catagen – which takes 10-14 days where hair detaches itself from the blood supply at the bottom of the hair bulb. Following this, the follicle enters resting stage, telogen, which takes 3 months. After that it enters anagen once again.