Bangladeshi national calendar

The Bangladeshi national calendar, known as Bengali calendar (Bengali: বঙ্গাব্দ, romanized: Bôṅgābdô) officially and commonly, is a civil calendar used in Bangladesh, alongside the Gregorian calendar. With roots in the ancient calendars of the region, it is based on Tarikh-e-Elahi (Divine Era), introduced by the Mughal Emperor Akbar on 10/11 March 1584. The calendar is generally 593 years behind the Gregorian calendar, meaning the year zero in the calendar is 593 CE.

The calendar is important for Bangladeshi agriculture, as well as festivals and traditional record keeping for revenue and taxation. Bangladeshi land revenues are still collected by the government in line with this calendar. The calendar's new year day, Pohela Boishakh, is a national holiday.

The government and newspapers of Bangladesh widely use the abbreviation B.S. (Bangla Son, or Bangla Sal, or Bangla Sombat) for Bangladeshi calendar era. For example, the last paragraph in the preamble of the Constitution of Bangladesh reads "In our Constituent Assembly, this eighteenth day of Kartick, 1379 B.S., corresponding to the fourth day of November, 1972 A.D., do hereby adopt, enact and give to ourselves this Constitution."