- By entering your menstrual cycle start and stop dates into a calendar, you can best predict your fertile days in a month to get pregnant. You will also need to know the length of your menstrual cycles, from the first day of your period to the first day of your next period. A calendar can help you keep track of this information since every woman's cycle is so different.
- Start by marking on your own calendar the first and last days of your period. Most calculators need this information, plus the length of your cycle, usually between about 21 to 35 days. Several online calculators can not only predict your fertility days, but also when you would most likely conceive and track the first few months of a pregnancy.
- You many not want to rely on an ovulation calendar for fertility reasons alone. It's also important to track your cycle for health reasons. It can be useful to a doctor, psychiatrist, fertility specialist or other medical specialist working with your body's needs. Also, keep track of days you feel cramping or note other emotional or physiological changes related to your menstrual cycle. Your body's changes can also contribute to understanding not only fertility issues, but also other health problems.
- If your menstrual cycles are irregular, you may have a hard time getting accurate information from an ovulation calculator. You may need to consult other fertility options such as basal temperature or cervical mucus. Ovulation calendars are estimates of fertile days, but it cannot predict changes in your body and with your hormones. For the best accuracy, combine an ovulation calendar with other fertility predictors.
- There are dozens of online fertility calculators you can use. There are some you can download to your desktop, too. Most calendars are free and do not require you to register or sign up with a web site. You can buy a pregnancy wheel or hand held calculator that can be with you at all times if necessary.
