My cycle is 28 days if I count from the first day of heavy
bleeding- however I spot for 3 days before the heavy
bleeding begins. Once the heavy
bleeding begins I bleed for 7 days (4 of which are very heavy) I use the Diva Cup (menstrual cup) because my periods are so heavy tampons aren't absorbent enough. Because I use the Diva Cup, I know that I bleed over 100 mls each period. From the time I start spotting to the time I stop bleeding is typically 10 days.