How Fast Does the Hair on Your Head Grow?
The hair on your head grows about half an inch each month. Your hair does not grow at the same rate throughout the day. It grows faster during the day than at night. It also grows faster in summer than in winter. Each hair grows for two to six years. Then it falls out and a new hair grows in to take its place.
The speed of hair growth is roughly 1.25 centimeters or 0.5 inches per month, being about 15 centimeters or 6 inches per year. With age the speed of hair growth might slow down to as little as 0.25 cm or 0.1 inch a month. Cell division is responsible for the hair growth cycle. The new cells push the hair forward to make it longer, so the new hair is added at the root.
During its life a hair goes through three phases of growth: the anagen, the telogen and the catagen. The anagen is the first phase with new hair growing in the hair bulb. The catagen is the following phase when hair stops growing because the cell division stopped. The telogen is the final phase. New hair starts growing in the papilla and finally the old hair falls out.
You may lose as many as hundred hairs from your head every day. But since you have around hundred thousand hairs on your head, you don’t miss them. When a person’s hair falls out and new hairs do not grow in as replacements, that person becomes bald.