Menstrual Period A woman’s menstrual cycle, or period, generally takes 28 to 32 days to complete. There are some women who have shorter cycles and some who have longer cycles. The only way to determine your cycle length is to track your periods on a calendar.

There are five phases of the menstrual cycle – menstrual, proliferative, ovulatory, luteal and ischemic. Your period comes on day one of the menstrual cycle and lasts for three to seven days, in most cases. The day your next period starts varies depending on many factors, but especially on the day you ovulate. The next menstrual period begins about 14 days after ovulation (range 12-16 days). So if you ovulate on day 14 of your cycle, then the next menstrual period begins around cycle day 28 (14+14), and if you ovulate on cycle day 21, then the next period usually begins on cycle day 35 (21+14). 

For example, if your period started on March 1st, you can expect your next period to start between March 29th and April 2nd.