The rate of hair growth depends on genetics and the shape of the hair follicles. This means that the rate of hair growth is slightly different depending on race.
For people of European origin, hair grows at the average rate of about 0.40 inches (or 1 centimeter) per month. For people of African descent, whose follicles are spiral shaped, the rate of growth tends to be somewhat slower at 0.31 inches (0.8 centimeters) per month. People of Asian descent tend to have the fastest growth rate at 0.50 inches per month (1.25 centimeters).
Normal hair growth in individuals may vary between the averages, from a low of about 0.2 inches per month (0.50 centimeters) to 0.60 inches per month (1.5 centimeters). Other factors that may affect hair growth are diet, hormones and exposure to UV radiation. Males and females grow hair at the same rates.