Calculating Your Cycle
Learning how to calculate the menstrual cycle is integral to a woman's health for several reasons. For one thing, if you want to become pregnant, you need to determine the point of your cycle at which you are most fertile (most likely to conceive). Also, if you have any problems concerning your gynecological health, your doctor will want to have information about the length of your cycle.
A normal, healthy cycle can last from anywhere between 23-35 days. If your cycle seems longer or shorter than this, you should probably speak to your doctor to make sure you don't have a medical issue. But in order to get a good measure of whether your cycle is too short or too long, you first must learn how to calculate your cycle with some measure of accuracy.
The length of the menstrual cycle is often misunderstood. Start with the premise that the counting is from the beginning of one menstrual period and ends with the first day of the next period. Day 1 of your cycle is the first day of your menstrual flow. If your range is longer or shorter than 23-35 days, chances are you aren't ovulating, though other causes must first be excluded.
Having an accurate chart of your cycle ensures that you and your doctor will be on the same page. If you tell your doctor, for instance, that your menstrual cycle is only 17 days long, and you're counting from the end of your period until the beginning of your next period, you'll be giving the physician an inaccurate picture which may lead to an incorrect diagnosis. In this example, if you have 7-day long periods, the length of your cycle is normal, since it lasts not 17 days but 24 days (17 plus 7). This is a normal cycle.
If you want to get pregnant, you'll want to determine at what point in your cycle it's most effective for you to have conception sex. If you wish to avoid pregnancy using the rhythm method, you will want to avoid having sex on those fertile days.
As mentioned above, the first day you see bleeding is cycle day 1. Mark it down on a calendar. Keep counting the days of your calendar until your next period arrives. The days between your two menstrual periods represent the length of your menstrual cycle. If your period starts on January 1, and your next period arrives on January 29, this means you have a cycle length of 28 days.
Continue to count and record until you have five cycles recorded. The count is reset to "day 1" each time you experience the first day of your period. At this point, it's possible to obtain an average cycle length. The average of these five months is more accurate than counting a single cycle.