The day of conception is very close to the day you ovulate– plus/minus 2 days. The ovulation day is tied to the end of a menstrual cycle, not to the begging. In fact, the ovarian cycle goes in 2 phases: first-the follicular and second-the luteal. Between these phases, a woman ovulates. The first (follicular) phase of the menstrual cycle can vary but the second (luteal) is generally constant. The luteal phase of the ovarian cycle is about 14 dayslong . That is because the existence of the yellow body (corpus luteum) usually lasts for about 14 days. A normal cycle duration is considered to be between the range of 21 to 35 days. If cycle a lasts 21, days ovulation occurs on the 7th day of the cycle. If cycle lasts for 35 days, ovulation occurs on the 21st day of the cycle. And ovulation occurs on the 14th day if cycle lasts 28 days. In most women, the menstrual cycle lasts for about 28 days.