Menstruation cycle length varies from woman to woman. Typically, you can determine menstruation cycle length by counting from the first day of vaginal bleeding in one cycle to the day before the first day of vaginal bleeding in the next cycle. This differs from the length of your menstrual period, which is usually counted from the first day of menstrual bleeding to the last day of bleeding within a menstrual cycle. Often, discussions of menstruation cycles include 28-day cycles, but this is not accurate for all women; a normal menstrual cycle may range from about 21 days to about 35 days in length. At times, however, women may have cycle lengths that are shorter or longer than these for various reasons.
When you are trying to determine your menstruation cycle length, it is important to keep in mind that a menstrual cycle includes not only your period, but also all the other days between menstruation and your next period. You can determine the length of your menstrual cycle by beginning your count on the first day of your menstrual period and ending your count with the day before your next menstrual period. For example if you begin counting on the first day of a period and your next period begins on day 28, your menstrual cycle is 27 days long.
Sometimes people confuse menstruation cycle length with menstrual period length. The two are not the same, however. Typically, you will count menstrual period length by beginning with the first day of your menstrual period and stopping with the last day of menstrual bleeding. Many women have periods that last for about five days, but longer or shorter periods are normal as well.
Once you have determined the length of your menstrual cycle, you may wonder whether it is normal. Typically, menstrual cycles that range from 21 days to 35 days in length are considered normal. Every woman is different, however, and it is possible that a longer or shorter cycle may still be normal for you. Sometimes, however, menstrual cycles are longer or shorter than normal because of some type of problem. For instance, a hormonal imbalance or delayed ovulation may cause changes in menstruation cycle length; even physical or emotional stress may cause changes in your cycle length.
It is important to note that your menstrual cycle length may not be the same every month. Your menstrual cycle could last for 27 days one month and then 25 the next. For this reason, you may use averaging to determine your typical cycle length. To do this, you may add the lengths of your last four cycles and then divide this number by four. Your answer is the average length of your menstrual cycle.