Is menstruation according to the lunar calendar or the solar calendar?

1, menstruation can be based on the lunar calendar and the solar calendar, because both lunar and solar calendars have time periods. The lunar calendar is generally 29-30 days, sometimes it may be February 28th, and the solar calendar is 30-3 1 day, so it can be used as a woman's menstrual cycle to infer menstrual time. But because the lunar calendar is not as easy to calculate as the solar calendar, the solar calendar algorithm is generally used.

2. The average woman's menstrual period is about 2 1-35 days. Take women's menstruation once every 28 days as an example. If a woman's menstrual period is 10 June 10.20, then the next menstrual period is probably 1 1. 17.