Why do I need to know the length of my average menstrual cycle? What if I don't know it exactly?
Ovulation occurs at different times for different women, depending largely on the average length of a woman’s cycle. On average, ovulation occurs about 14 days before your next period starts. Therefore, it is easier to figure out when to start testing if you know your average cycle length. For example, using the diagram in the Product Instructions, if you have a 28-day cycle you are likely to experience ovulation around day 14 after the first day of your last menstrual period, so it is recommended to begin daily testing 12 days after the start of your last period. If you do not know your average cycle length, use the shortest cycle length from the previous six months. Input this information into our Ovulation Calculator to determine what day to start testing.