Q: Is a normal menstrual cycle 28 days long?
A: Normal menstrual cycle can vary from about 21 to 35 days. Cycles can vary from one woman to another as well as for each woman, and ovulation does not always happen on the exact same day, even in women with regular cycles.
If you don't know the exact date of ovulation, then use our ovulation calculator to the approximate first day of your last menstrual period in a 28-day cycle. If your cycles are longer or shorter than 28 days, then the day of ovulation may change, and this calculator takes that into consideration when calculating your estimated due date.