Regular haircut
Human scalp hair grows on average about one eighth inch per week or one half inch per month. Most clipper guards are numbered in eighths of an inch. The number of the guard denotes the number of weeks of hair growth left on the scalp when a clipper with a certain numbered guard is guided over the head with the guard in contact with the scalp. A #1 guard leaves 1/8 inch (3 mm), one week's growth of hair, on the scalp; a #2 guard leaves 2/8" (6.3 mm), two weeks' hair growth, on the scalp; a #3 guard leaves 3/8" (9 mm), three weeks' hair growth on the scalp; and so on.
Hair care
There are various reasons for hair loss, most commonly hormonal issues. Fluctuations in hormones will often show in the hair. Not all hair loss is related to what is known as male pattern baldness, women can suffer from baldness just as men do. Formulas for addressing this specific cause of lack of hair growth yet typically they require around three months of consistent use for results to begin to appear. Cessation may also mean that gained growth may dissipate.