The sprayer delivers a generous volume of product to the scalp and with massage, can be massaged to cover twice the area and on fine textured hair, on three times the area. The amount of product required depends on whether the hair loss is limited to a designated area, or all over the head. The average user is specifically losing hair in designated spots. If you are losing hair all over,  distribute each pump further by massaging to a larger area. This will help greatly, as the pumps are powerful and deliver a generous amount of product to the scalp. On average, one bottle will last four weeks however if hair loss is in a designated area only, the bottle will last for longer.