The way to calculate the ovulation period of 28 days of menstrual cycle, menstruation is regular, ovulation should be from about 14 days before the next menstrual period is regarded as ovulation, and then the accurate test can be through the vaginal ultrasound to monitor the follicle. The follicles need to be about 1.8cm at the time of ovulation. You can start monitoring the follicle’s development on the 9th day of your period, or you can directly calculate the approximate time of ovulation and then go for an ultrasound. If your period is regular, you can use ovulation test paper to test for ovulation, and then have intercourse when the test is strong positive. This is also the best time for conception, and you can monitor ovulation by measuring your body temperature, because when you are about to ovulate, your body temperature should rise by 0.1-0.2 degrees Celsius, which indicates that you are about to ovulate.