How hair grows

Hair grows out of little pockets in your skin, called follicles. Here's how it happens:

  1. Your hair begins growing from a root in the bottom of the follicle. The root is made up of cells of protein.
  2. Blood from the blood vessels in your scalp feeds the root, which creates more cells and makes the hair grow. 
  3. The hair gets pushed up through the skin as it grows, passing an oil gland along the way. The oil gland adds oil to the hair and keeps it shiny and soft. It can make it greasy, too. That's why you need to wash your hair.
  4. The hair dies by the time it is long enough to poke out through the skin. Yes, hair is dead. That's why it doesn't hurt to get a haircut.
 

                Hair follicles in skinAn illustration of hair follicles on skin.

              

Hair on the rest of your body goes through this same process, but the whole cycle only lasts for a month or so. That's why body hair does not grow very long in length like the hair on your head does.

Here are some facts about follicles and your hair:

  • You are born with all of the follicles you will ever have — about 5 million.
  • You have about 100,000 follicles on your scalp, which is the skin on your head.
  • Hair grows very fast and male hair grows faster than female hair. The only part of your body that grows faster is bone marrow, the soft stuff inside your bones. The hair on your head grows about 6 inches a year. So, even though it's one of the fastest-growing things on your body, it takes a while to grow it really long.
  • You lose about 50 to 100 hairs a day. That's because the follicles don't all grow hair at the same time. Each scalp follicle grows hair for a few years and then takes a break. When a follicle is on a break, the hair in the follicle falls out. Because the follicles take breaks at different times and the other hairs keep growing, you probably don't notice when you lose hairs.
  • Some follicles stop growing hair as you get older. This happens more in some people than in others. That's why some people get thinner hair when they get older, or go bald.

Next: Why everyone's hair is different.