You'll need to track the length of each cycle for 8 cycles to predict the first and last fertile day of your current cycle.
Cervical Mucus Method
Your cervix will produce different levels of mucus depending on where you are in your cycle. In addition to flow, color and consistency is also important for tracking mucus pattern.
Standard Days Method
Developed by the Institute for Reproductive Health at Georgetown University and uses CycleBeads to keep track of your cycle. Only suitable for women with regular cycles between 26-32 days.
A combination of multiple fertility awareness methods, most often the temperature method, cervical mucus method, and calendar method.
Requires close tracking of your basal body temperature every morning when you get up. Your body temperature will be lower at the beginning of your cycle and increases as you ovulate.
Requires checking for mucus every day. If mucus is detected, you need to abstain from sex that day and also the next day.