Statistical Averages of the Human Hair

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.