The average human scalp has anywhere from 120,000 to 180,000 hairs.
The average hair grows at a rate of about 1/2 inch per month.
The average person's hair grows 6 inches per year.
Hair has an average growth cycle of 4-6 years.
Most people can grow their hair between 24 and 36 inches.
Some people have a very short hair growth cycle, only 1 & 1/2 years,
this means their hair will grow to a maximum length of nine inches.
Ten years seems to be the maximum growth cycle. This accounts for people with extremely long hair (ex: Crystal Gayle), reaching 60 inches.