The Ovulation Calendar Method predicts ovulation by looking at a woman's menstrual history - recognizing calendrical patterns and isolating the most fertile times for conceiving a baby. Fertility charting combines the calendar method with other methods of ovulation and fertility prediction.

The Ovulation Calendar Method allows you to chart fertility and determine when ovulation takes place in your cycle. The calendar method involves keeping a written record of the history of your menstrual cycles - which yields your unique 'fertility statistics' (including trends that may indicate irregularities).

Our Ovulation Calculator operates on the same principle, predicting ovulation by factoring the first day of your last menstrual cycle, the average length of your cycles, as well as the duration of your luteal phase. Maintaining a written ovulation calendar allows you to monitor these useful 'fertility statistics' - and determine irregularities or unique trends in your cycle.

The calendar method is designed to predict general trends in fertility based on past menstrual patterns - and is therefore limited in terms of "pinpoint accuracy". The more regular a woman's cycle, the more effective the calendar method is - and perceiving ovulation patterns begins to crystallize after a few months of maintaining records.

 *Click here to use our online ovulation calendar.

With the ovulation calendar method, a written record is kept using a calendar to follow the patterns of each cycle. Each cycle begins with the first day of one's menstrual period and ends with - but does not include - first day of the next (which should be recorded as the first day of the next cycle).

How to Chart your Ovulation Calendar

The day menstrual flow begins is 'Day One'. Circle this date on your calendar or chart and notate as 'Day One'. For each following month, circle Day One and continue this for for at least 7-8 months. Continue maintaining a record of the number of days in each cycle. When bleeding starts, circle the date on your calendar.

To determine the first day you are likely to ovulate, examine your records from previous months, find the shortest cycle, and subtract 18 from the total number of days in your cycle.

For example, if your shortest cycle is 28 days long, subtract 18 from 28, which leaves 10. Starting with the date you circled (Day One, the first day of your current cycle) count ahead ten days and draw an O (for 'ovulation') through that second date. This day will be the date you are most likely to become fertile - and frequency of intercourse should increase as the duration of this fertile period will extend approximately 5 days or more.

While the calendar method is helpful in predicting fertility, it is not extremely precise and does not account for cycle irregularities. Here, fertility charting augments the calendar method by taking into account several other methods of prediction ovulation - from monitoring changes in body temperature to ovulation testing using home predictor kits.

Fertility Charting and Ovulation Prediction

Fertility charting unifies several methods of ovulation prediction to help focus in and pinpoint your most fertile times. Because it combines complementary methods, a fertility chart allows you to better understand the unique dynamic of your menstrual cycle and time intercourse with increasing accuracy.

Fertility charting unites calendrical recording of cycle days with monitoring other physiological symptoms, as well as BBT charting, cervix and cervical mucus observations, and ovulation testing.

By charting all these variables - and looking at patterns and relationships - you will be able to determine your most fertile time for conceiving a baby with increasing accuracy. To look at each of these variables (or fertility prediction methods) in detail, click on the links below (and download a fertility chart).

> Read More about Fertility Charting and Download a Fertility Chart
> Learn About the Pre-Pregnancy Check-Up

*Click here to use our online ovulation calendar.