Monthly Period tracker! Best period tracking system with privacy! Log, observe, understand your fertility, flow, hormonal changes and mood cycles. Plus we included the Chinese calendar. more… Welcome to Monthly! You can easily follow your menstrual cycle and special days with the simple and useful app we have prepared for you. The Monthly app can show you when your next menstrual cycle is, most fertile dates, PMS cycles. You can also keep track of the hormonal changes and mood cycles throughout the month and plan your days accordingly. Fertility tracking is proven to increase positive results for conception. the Monthly app is the easiest way to track it! We have also included the Chinese calendar for those who want to take it into consideration. Using the calendar as well as your birth date, we can make assumptions about due date and gender of the baby the traditional Chinese calendar that we prepared. The data you log into Monthly app is not shared with third parties.