Five days. According to the relevant information query, May 8th to May 12 is a ***5 days. According to the perpetual calendar, May 8th to May 12 is five days. The perpetual calendar is the oldest solar calendar in ancient legends of China. The name of the perpetual calendar comes from a man named Wannian in Shang Dynasty, who was the editor of this calendar. In order to commemorate his achievements, this calendar was named perpetual calendar.