Period calendar I created with my own need to control the menstrual cycle, I tested, and now I share it with you. I am addressing it for those of us who do not remember the day of your last menstrual period, for those who wonder whether the day of an important party may also prove to be "that day", and for those who are trying for a baby and want to calculate when the biggest chance day falls. On the basis of the length of the cycle, Period calendar calculates and selects the color of the probable date of the next menstrual period start, preceding it infertile, and also shows fertility time. It has memory of past cycles, so you create the history of the biological rhythm of your body. It also remember the date held or scheduled doctor visits and medications you take.