The ovulation date of women is generally about 14 days before the next menstrual cramps. On the first day of the next menstrual cramps, the countdown to 14 days or 14 days is the ovulation day. Ovulation day and the first 5 days and the last 4 days together are called ovulation periods. For example, a woman's menstrual cycle is 28 days, the first day of the menstrual cramps on December 2nd, then the next menstrual cramps is December 30 (December 2 plus 28 days), and then from December If you subtract 14 days on the 30th, December 16th is the day of ovulation. Ovulation day and the first 5 days and 4 days later, that is, December 11-20 for ovulation.