Sometimes a woman's temperature does not rise with ovulation, or there are other difficulties with using the basal temperature method of predicting ovulation.
There are two systems used in calculating when a women is about to ovulate. The American System which dates back to early times and the Ovulation System. The Ovulation Calculator is the most accepted and considered the most accurate. The accuracy of this method of course will depend on you. The Ovulation Calculator often helps determine when it is a good time to have sex if you are wanting to conceive in order to have a baby. The most effective way is when a woman becomes fertile.
Calculator for determining your ovulation periods based on the first day of your last menstruation period.