The Javanese calendar is the calendar of the Javanese people. It is used concurrently with two other calendars, the Gregorian calendar and the Islamic calendar. The Gregorian calendar is the official calendar of the Republic of Indonesia and civil society, while the Islamic calendar is used by Muslims and Indonesian government for religious worship and deciding relevant Islamic holidays.
The Javanese calendar is used by the main ethnicities of Java island: Javanese, Madurese and Sundanese people – primarily as a cultural icon, a cultural identifier and as an object and tradition of antiquity to be kept alive. The Javanese calendar is used for cultural and metaphysical purposes of these Javanese peoples
The current system of Javanese calendar was inaugurated by Sultan Agung of Mataram in the Gregorian year 1633. Prior to that, Javanese had used the Hindu calendar or Saka calendar which that starts in 78 CE and uses the solar cycle for calculating time. Sultan Agung's calendar retained the Saka calendar year counting but differs by using the same lunar year measurement system as the Islamic calendar, rather than using the old solar year. Occasionally it is referred by its Latin name Anno Javanico or AJ (Javanese Year).