When a woman menstruates, her body is shedding the lining of the uterus (womb). Menstrual blood flows from the uterus through the small opening in the cervix, and passes out of the body through the vagina. Most menstrual periods last from three to five days, but can vary. A menstrual cycle is counted from the first day of one menstrual period to the first day of the next period. Many women have a dedicated menstrual calendar to calculate their menstrual cycle period:
An estimated menstrual cycle period can be calculated by following steps 1 through 3:
- You need to determine the first day of your last menstrual period.
- Knowing your menstrual cycle length. This is the number of days from the first day of your period until the last day before your next period.
- Enter the date and menstrual cycle length, click the button and you'll calculate the next period(s).
Learn How to Calculate Menstrual Cycles Manually
- Get a calendar. This can be either a paper calendar or one on your computer, phone, or tablet.
- Mark the FIRST day of your LAST period with an "X". This is day #1
- Count forward however many days your menstrual cycle normally is before you start. If you don't know, then just count 28 days.
- Put your initials or some other identifying mark on the last day. This is when your period should start.
That's it! If you have never monitored your period before, after several months you'll be able to figure out your actual cycle length and adjust your calculations accordingly.