A free app for Android, by bomcomes.

Bom Calendar – Period Tracker is the best app to keep track of your menstrual cycle. It is designed to help you get to know yourself better and understand your lifestyle. It is useful for couples as well as for women who are not in a relationship. It is a simple and intuitive app. You can use it even if you have irregular periods.

Bom Calendar will help you to:

Get to know your menstrual cycle and understand your lifestyle. See the probability of pregnancy every day and know what to expect every day. Be prepared for any eventuality. Know what to do if you think you are pregnant.

Bom Calendar uses the same standard contraceptive guidelines and period calculation methods used by the American Board of OBGYN to predict the probability of pregnancy and the cycle.