The Islamic New Year is the day that marks the beginning of a new Islamic calendar year, and is the day on which the year count is incremented. The first day of the year is observed on the first day of Muharram, the first month in the Islamic calendar. Since the Islamic year is 11 to 12 days shorter than the Gregorian year, the Islamic new year does not come on the same day of the Gregorian calendar every year. While some Islamic organizations prefer determining the new month (and hence the new year) dates by local sighting of the moon, most Islamic institutions and countries, including Saudi Arabia, follow astronomical calculations to determine future dates of the Islamic calendar.