Women's Calendar is an excellent tool not only girls but also women. It has many useful features: forecast the duration of menses and successful ovulation, reminders about upcoming cycles, regular recording of health data (mood, symptoms, number of drops, notes, sexual intercourse, temperature, potential devices tablets), show BMI (weight/height), password protection from prying eyes, reminders of the use of norms of water a day and so on. Life instantly easier, just try.