The rate of hair growth, often measured as "how much does your hair grow in a day," represents the average daily increase in hair length. As an example, hair typically grows around 0.5 millimeters per day, which translates to approximately half an inch per month.
Understanding hair growth is important for maintaining healthy hair and scalp. Regular hair care routines and treatments can benefit from knowledge of growth rates. Historically, hair growth has been studied to develop hair loss treatments and hair transplantation techniques.