Ramadan has no fixed dates, but depends on the lunar calendar. The beginning of each month of the Islamic lunar calendar is the day following the new moon. The lunar calendar is shorter than the Gregorian calendar for about 11 days, so the date of the beginning of Ramadan is shifted about 11 days ago annually. In 2012, the Ramadan festival was held from July 20 to August 19. In 2013, it is expected approximately from July 11 to August 9.

This holiday "moves" by the date (as our Easter) In 2013 - from July 11 to August 9.