The day of ovulation is calculated as 14 days before the first day of the next menstrual period, only for menstrual cycles of about 28 days.
The calculation of the day of ovulation is related to the menstrual cycle and the exact time is variable. Generally speaking, counting down 14 days or subtracting 14 days from the first day of the next menstrual period is the day of ovulation, and the day of ovulation and the 5 days before and 4 days after the day of ovulation together is the period of ovulation.
Specifically, a woman’s physiological cycle has a total of 21-35 days, mainly including the follicular phase, the ovulation phase and the luteal phase, of which the time of ovulation is not fixed. If the menstrual cycle is 28 days, then ovulation occurs on the 14th day of menstruation. If your menstrual cycle is 35 days long, ovulation occurs on the 21st day of your period.
If the menstrual cycle is irregular, then the day of ovulation is difficult to calculate, and needs to be determined by ovulation test paper or ultrasound.