Ovulation calendars essentially provide no more than an automatic calculation of the days you are most likely to conceive during one cycle for you but that is just what you need if you are planning to increase your chances of getting pregnant. The free and personalized ovulation calendar will ask you to enter as much information about your cycle as you can. With data about the date your last menstrual period started, and the average number of days in your cycles, an ovulation calendar can make a fairly accurate prediction of the expected date of your ovulation. If you are also using other methods to determine when you are ovulating, and you know the length of your luteal phase that part of the menstrual cycle that lasts from ovulation until menstruation the calculation offered by ovulation calendars is even more likely to be spot on.
Unlike ovulation predictor kits, which are a great tool for women who want to determine the exact time of ovulation, ovulation calendars will give you information about the days at which you are expected to be most fertile in advance. This gives you the opportunity to plan in advance, and enables you to make use of the whole window of fertility; the days before an egg will be released, as well as during the actual ovulation.