Cycle Length Calculator

Enter the first day of your last few menstrual periods to view your shortest and longest cycles and to calculate your average cycle length. The more dates you enter the more accurate the results will be.

Once you have your average cycle length you can use this number in our Ovulation Calculator which can help you pinpoint when it is best to try to get pregnant by predicting your most fertile days.

Menstrual Cycle Start Dates:

Click the icon to use the popup calendar or use format mm/dd/yyyy.