Australian Stories may contain the names and images of Aboriginal and Torres Strait Islander people now deceased. Australian Stories also contain links to sites that may use images of Aboriginal and Islander people now deceased.
1 Record the number of days in each cycle, including the day you start your period. 2  The last day of each cycle is the day before your next period starts. 3  Keep tracking your cycle this way for eight to twelve cycles. 4  The more cycles you have to reference, the more accurate the calendar method will be.
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 the: 1  Ovulation Calculator which can help you pinpoint when it is best to try to get pregnant by predicting your most fertile days. 2  Intercourse Timing Calculator to help find the best times to have intercourse when trying to get pregnant.