Gregorian-Lunar calendar conversion

Lunar and solar calendars:

The lunar-solar calendar is a system that takes into account the cycles of the moon orbiting Earth and Earth orbiting the sun. The average length of the lunar months in this calendar is close to the synodic month, and the average length of the years is close to the tropical year, making it a "lunar month and solar year" type of calendar. It allows each year to roughly align with the seasons while keeping the dates of each month in line with the moon. Its drawback

China's calendar has been continuously improved, enriched, and refined over thousands of years, evolving into the lunar calendar used today. Essentially, the lunar calendar is a combination of the solar and lunar calendars, primarily based on the moon's cycle, while also taking into account the Earth's orbit around the sun.