1. Hair is the second fastest growing tissue in the body after bone marrow
The rate or speed of hair growth is about 1.25 centimetres or 0.5 inches per month, or about 15 centimetres or 6 inches per year. Pubic and axillary (armpit) hair grows almost as fast as scalp hair at 15 but slows with age and has a much faster follicle turn over time.
2. A healthy strand of hair can stretch an additional 30% when it’s wet
Hair Elasticity. The hair’s elasticity is the measure of how much the hair will stretch (and return to a normal state). Healthy hair, when wet, will stretch up to 30% of its original length and return to its normal shape without breaking, while dry hair will only stretch about 20%.
3. A single hair has a lifespan of about five years
New strands of hair, which have an average life cycle of 5 years, replace those that we lose daily. Each hair follicle produces a new hair, which then grows in successive cycles before falling out. The life cycle of a hair is divided into three phases: anagen, catagen and telogen.