DISCLAIMER: The information given on this site is for general information only. It should not be considered as medical advice. As withall physical and medical conditions you should always consult your doctor or health care professional [Expired] Hair is genuinely individual and cannot be summed up in a few facts & figures. That said, vital statistics can sometimes be useful. However, since every hair and head of hair is absolutely unique, the figures on this page are of course only averages Take a look

1. Hair is the fastest growing tissue in thebody, second only to bone marrow.
2. The diameter of an averagesingle hair is 58 to 100 microns. However, since thecross section of a hair is elliptical, the termdiameter is not totally accurate.A micron is one millionth of a meter, or one thousandth of a millimeter - it therefore takes 10 to 20 hairs "piled up" together to obtain a thickness of one millimeter.
3. The averagenumber of hairs per squarecentimeter of scalp is 250. This figure varies between 200 and 300 according to thearea of scalp in question as also thethickness of thehair.
4. The total surface area of an average head of hair 20 centimeters long would be 6 meters squared. This is an important figure, as when shampooing for example, this is thesurface that must be washed. Since the surface area of thescalp is 600 cm², a head of hair 20 centimeters long therefore occupies an area 100 times greater than its place of origin.
5. The averagespeed at which hair grows is 1cmper month. This corresponds to a daily growth rate in excess of 0.3 mmper day and an annual growth of 12 centimeters per hair. By applying these figures to the entire head of hair, we see that it is produced at the rate of more than a 36 meters aday, some 1.1 kilometers per month, or more than 13 kilometers ayear! In terms of weight, for the entire head of hair this represents 0.2 grams per day, 6 grams a month or 72 grams year. Since hair grows from its roots, thetip of a hair 12 cmlong will be one year old. But as asingle hair has on average a threeyear growth cycle, it is rare to see hair longer than one meter, which represents over eight years of growth However, the world record for hair length stands at 4.2 meters. If this hair had grown at a normal rate, its tips would be 35 years old!
6. The averageweight of a head of hair according to the length of the hair making it up is 5 to 200 grams. 30% of its own weight, the percentage of weight in water that ahair in good condition can absorb. If it has been weakened, this percentage can reach 45%
7. 90% of scalp hairs are growing and 10% are resting at any one time.
8. It is normal to lose 100 hairs per day fromthe scalp and you can lose over 50%of your scalp hairs before it is apparent to anyone.
9. Many drugs can cause hair loss.
10. Thyroid imbalance and iron deficiency are reversible causes of hair loss.
11. Over 50%of men by age 50 have male pattern hair loss.
12. Forty percent of women by the timethey reach menopause will have female pattern (hereditary) hair loss
13. A human hair is stronger than copper wire of the same thickness & thecombined strength of a head  of human hair is capable of supporting theweight equivalent of 99 people
14. Healthy hair is highly elastic and can stretch 20 or 30 percent before snapping
15. Between the ages of 40 and 50 women tend to lose about 20 percent of their hair
16. Hair grows faster in thesummer, during sleep and between theages of 16 and 24
17. There are 100,000 hairs on the average adult head with blondes having most (120,000) and redheads least (80,000)