How fast does hair grow?
Scalp hair grows about 1 to 1.25 centimeters (about half an inch) a month on average, which adds up to roughly 15 centimeters (6 inches) a year.
Hair grows in cycles. During the growth phase, called anagen, which lasts two to seven years for scalp hair, a hair grows steadily. It then enters a short transition phase and a resting phase, after which it falls out and a new hair begins. At any time, about 85 to 90 percent of scalp hairs are growing.
The length of the growth phase decides how long your hair can get. People with long growth phases can grow hair past their waist, while others find their hair stops at shoulder length. Hair on the eyebrows and arms has a much shorter growth phase, so it stays short.
What affects hair growth
Genetics, age, hormones and overall health all influence growth. Hair tends to grow fastest between about ages 15 and 30. Severe stress, illness, some medicines and poor nutrition can slow growth or cause shedding. Cutting hair does not make it grow faster, because growth happens at the root.
Did You Know?
It is normal to lose about 50 to 100 scalp hairs a day. Most people have around 100,000 hairs on their head.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.