Ovulation is calculated according to the length of the menstrual cycle and the regularity of menstruation. Generally speaking, ovulation occurs about 14 days before the next menstrual period is called the day of ovulation, 5 days before and 4 days after the day of ovulation are called the ovulation period.
If you have regular menstrual cycles of 30 days, then the 19th menstruation, the next menstruation should also come on the 19th of the next month, then the 5th of the next month is the day of ovulation, 5 days before and 4 days after the day of ovulation are called ovulation.
After the egg is discharged, it dies on its own if it fails to meet a sperm. Hormonal changes occur in the body and the endometrium is ischemic and necrotic and sheds, resulting in menstruation. If menstruation is irregular, the time of ovulation is also irregular and there is no way to predict it well.
So the exact time of ovulation can be determined by your menstrual period and the length of your menstrual cycle. For women with irregular periods, ovulation time is not predictable based on the timing of your period. You can choose to monitor your basal body temperature, and ideally you can use ultrasound to monitor follicular development and ovulation, which is currently a more secure method of monitoring ovulation.