One daily sanitary napkin is 15ml if it is completely soaked; if you use night sanitary napkin, it is 20ml if it is completely soaked; two daily sanitary napkins are 30ml of menstrual volume if they are completely soaked. The normal menstrual volume is 5-60ml, less than 5ml is too little menstruation, more than 80ml is too much menstruation, 30ml is the normal menstrual volume. If there is an increase in menstrual flow, it is not normal and further examination is needed. If the menstrual volume is too low, it may also be caused by endocrine disorder and further examination and treatment is needed.