Epoch

Calendar eras

Regnal eras

Pre-modern eras

• Olympiads, the ancient Greek era of four-year periods between Olympic Games, beginning in 776 BC.
• Ab urbe condita, used in the Roman imperial period.
• The Anno Domini or "Common Era" era, still in use with the Gregorian and Julian calendars today, marks the Incarnation of Jesus as calculated in the 6th century by Dionysius Exiguus.
• Anno Mundi as used in the Byzantine calendar.
• Anno Mundi as used in the Hebrew calendar.
• The Islamic calendar counts "lunar years" by Anno Hegiræ or AH era. The year count shifts relative to the solar year as the calendar is purely lunar. The official Iranian calendar also dates from the hijra, but as it is a solar calendar its year numbering does not coincide with the religious calendar.
• The term Hindu calendar may refer to a number of traditional Indian calendars. A notable example of a Hindu epoch is the Vikram Samvat, also used in modern times as "national calendar" of Nepal and Bangladesh.
• Buddhist calendars tend to use the epoch of 544 BC.

  Modern eras

• The Baha'i calendar is dated from the vernal equinox of the year the Báb proclaimed his religion. Years are grouped in Váḥids of 19 years, and Kull-i-Shay's of 361 years.
• In Thailand in 1888 King Chulalongkorn decreed a National Thai Era dating from the founding of Bangkok on April 6, 1782. In 1912, New Year's Day was shifted to April 1. In 1941, Prime Minister Phibunsongkhram decided to count the years since 543 BC. This is the Thai solar calendar using the Thai Buddhist Era. Except for this era, it is the Gregorian calendar.
• In the French Republican Calendar, a calendar used by the French government for about twelve years from late 1793, the epoch was the beginning of the "Republican Era", September 22, 1792.
• The Indian national calendar, introduced in 1957, follows the Saka era.
• The Minguo calendar used by officials of Taiwan and its predecessor dates from January 1, 1912, the first year after the Xinhai Revolution, which overthrew the Qing Empire.
• North Korea uses a system that starts in 1912, the year of the birth of its founder Kim Il-Sung.
• In the scientific Before Present system of numbering years for purposes of radiocarbon dating, the reference date is January 1, 1950.
• Different branches of Freemasonry have selected different years to date their documents according to a Masonic era, such as the Anno Lucis.