How hair grows

Your hair grows about 1.3cm a month

Human hair is made of keratin: a protein produced in tiny cavities called follicles, which reside in the dermis layer of the skin. Hair exists everywhere on the body apart from the soles of the feet and palms of the hands, but is mostly so fine that it is practically invisible.

As new hair cells are produced by the follicles, the old ones are pushed through the surface of the skin, so the hair that you can see growing – for example on the head – is actually made of a string of dead keratin cells.

Each hair follicle has its own lifecycle, consisting of a growth phase (anagen), which can last between two and six years, and a resting phase (telogen) which lasts a few months. At the end of the resting phase the hair is shed and the cycle begins again. Your hair grows about 1.3 cm a month; faster in summer than in winter. This means that an average full-length hair can be from 30 to 80 cm in length. On the average adult head there are approximately 100,000 to 150,000 hairs, and it is normal to shed 50 to 100 hairs every single day because new hair is growing at the same time.

Find out more about male pattern baldness