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.
Calculate Your Cycle and instantly see where you are in your cycle today! How to calculate average menstrual cycle length... Use MyMonthlyCycles.com FREE Period Tracking Calendar! and your cycle statistics auto-calculate as you track! 1  Setup your free account at MyMonthlyCycles. 2  Use the Period Tracker. 3  Click your period dates.