MomJunction’s period calendar requires you to input the date of your last menstrual period date to calculate your monthly period. The date here refers to the starting date of the last period cycle, not the ending one.
The second input requires you to give the average length of time between your periods. Since the term varies from person to person, it’s not wise to assume the figure. You must be as accurate as possible to determine your most fertile days if you are planning to conceive.
Once you’ve shared the inputs, the period calculator will show you the result. It won’t just give you a heads up on your next period start date for the next 12 cycles, but will tell you about your most fertile days and if you are late for your period cycle. Even if your period is delayed, you will know the next expected date of your period. This way, you can keep a track of the length of your menstrual cycle and the number of days it lasted.