Nanbang Ovulation & Safety Period Calculator

Nanbang Ovulation Period & Safe Period Calculator can automatically calculate the safe period after filling in the menstrual cycle and the time of the last menstrual period.

Relevant knowledge

The safe period refers to a female menstrual cycle, which is related to menstruation. It is normal for a woman's menstrual cycle to last from 26 to 35 days. There is a gap of about 10 days, which shows that the safe period may not be as safe as expected. In Hong Kong, the safe period is generally regarded as the 7 days before and 7 days after menstruation, so it is commonly known as the first seven days and the last seven days.

Lampang Women’s Safety Period 1.3: The accuracy of the repair test is as high as 99%

Principles of safe period contraception

Taking the 28-day menstrual cycle as an example, 3 to 5 days after the first menstrual period can be called the "menstrual period". After cleansing, the first phase of the safety period begins. The two safe periods between menstrual cycles are separated by the ovulation period. Ovulation is almost certainly on the 14th day before the next period, or 5 days earlier or 4 days later. This is also the so-called danger period. Because male sperm can survive in the female body for 3 days, it is necessary to advance the dangerous period 5 days before the aforementioned 14 days by 3 days to prepare for unexpected events. This day is the end of the first phase of the safety period. The second phase of the safe period starts from the day 4 days after the aforementioned 14 days until the day of the second menstruation. It can be seen that the safety period of the second stage is safer than that of the first stage. Ovulation usually occurs 12 to 22 days after menstruation, entering the dangerous period.