On average, human hair grows at a rate of about ½ millimeter a day. This averages out to a rate of approximately ½ inch per month.
Genetics, hormones and age all play a role in how fast an individual's hair grows. Hair grows the same rate all over the head. If one area of the hair seems to grow faster then the rest, it is an illusion.
Hair grows at an average rate of 6 inches per year. There are 100,000 hairs on the average person's head. Hair strands last up to six years before being replaced by new hair.