Bengali calendar

The Bengali Calendar or Bangla Calendar (বঙ্গাব্দ Bônggabdô or Banggabda) is a solar calendar used in the region of Bengal. A revised version of the calendar is the national and official calendar in Bangladesh and an earlier version of the calendar is followed in the Indian states of West Bengal, Tripura and Assam. The New Year in the Bengali calendar is known as Pôhela Bôishakh.

The Bengali Era (BS) or Anno Bengal (AB, Latin for: in the year of Bengal), the Bengali year (বাংলা সন Bangla Sôn, বাংলা সাল Bangla sal) is 594 less than the AD or CE year in the Gregorian calendar if it is before Pôhela Bôishakh, or 593 less if after Pôhela Bôishakh.

The revised version of the Bengali calendar was officially adopted in Bangladesh in 1987. However, it is not followed in India where the unrevised (non-revised) traditional version continues to be followed due to occurrence of Hindu festivals based on a particular sidereal solar day.[1]


The Bengali calendar is a solar calendar.[1][2]

The origin of Bônggabdô or Bengali Year (Bangla Year) is debated, with primarily two hypotheses. The development of the Bengali calendar is often attributed to King of Gour, Shashanka as the starting date (12 or 14 April 594 CE) falls squarely within his reign.[1][3] The solar calendar is based on the Surya Siddhanta, a Sanskrit astronomical text.[1]

Another theory is that the calendar was developed by Alauddin Husain Shah (reign 1494–1519), a Hussain Shahi sultan of Bengal by combining the lunar Islamic calendar (Hijri) with the solar calendar, prevalent in Bengal.[3]

All theories agree that the Mughal Emperor, Akbar (reign 1556 – 1605) was instrumental in "promulgating" the Bengali calendar. Akbar modified, developed and re introduced the Bengali Calendar in order to make tax collection easier in Bengal. The calendar was then called as Tarikh-e-Elahi (তারিখ-ই ইলাহি). Akbar changed the practice of agricultural tax collection which had been according to the Islamic calendar and ordered an improvement of the calendar systems, because the lunar Islamic calendar did not agree with the harvest sessions and the farmers faced severe difficulties in paying taxes out of season. Some sources credit the idea to the finance minister of Akbar, Todar Mal.[1][2][3]

Akbar's royal astronomer Fathullah Shirazi developed the Bengali calendar, by synthesizing the Lunar Islamic and Solar Hindu calendars. The calendar started with the Islamic calendar value, but the Sanskrit month names were used from the earlier version.[1] The distinctive characteristic of the Bengali year was that rather than being a lunar calendar, it was based on a union of the solar and lunar year. This was essentially a great promotion as the solar and lunar years were formulated in very diverse systems.

Primarily this calendar was named as "Fasli Sôn" and then "Bônggabdô". The Bengali Year was launched on 1584 AD or 992 AH (Hijri), but was dated from the year 1556 AD or 963 AH. This was the day that Akbar defeated Hemu in the clash of Panipat to ascend the throne. The month of Muharram in the year 963 AH was equal to the month of Boishakh in the Bengali calendar, and so Boishakh month has continued to be the first month of the Bengali calendar.[4]

In the "Tarikh-e-Elahi" version of the calendar, each day of the month had a separate name, and the months had different names from what they have now. Akbar's grandson Shah Jahan reformed the calendar to use a seven-day week that begins on Sunday, and the names of the months were changed at an unknown time to match the month names of the existing Saka calendar.[2][5]



The Bengali calendar consists of 6 seasons (Summer, Rainy/Monsoon, Autumn, Late Autumn, Winter and Spring), known as Rreetu ঋতু or Kal কাল, with each season comprising two months, starting from Pôhela Bôishakh.

As the traditional unrevised Bengali calendar used in West Bengal is sidereal and does not correspond to the real seasons in Bengal region and also does not correspond to the actual tropical movement of the earth. Hence after some centuries the months will shift far away from the actual seasons. But the new revised tropical version of the Bengali calendar used in Bangladesh will continue to maintain the seasons on time as mentioned above.


The names of the twelve months of the modern Bengali calendar are based on and derived from the ancient astronomical texts of Surya Siddhanta[4] which are the names of the নক্ষত্র nôkkhôtrô (lunar mansions): locations of the moon with respect to particular stars during the lunar cycle.

In the calendar originally introduced by Akbar in the year 1584 AD, the months were named কারওয়ারদিন (Karwardin), আর্দি (Ardi), খোরদাদ (Khordad), তীর (Teer), আমারদাদ (Amardad), শাহারিবার (Shahribar), ভিহিসু (Bihisu), আবান (Aban), আজার (Azar), দে (Dai), বাহমান (Bahaman) and ইসফান্দা মিজ (Isfanda Miz)[4] This was changed later, but it is not known when the change was made.[5]

Month name
Romanization Days
(Traditional non-revised
sidereal version
- India)
(New revised
tropical version
- Bangladesh)
Traditional Season
in Bengal
Corresponding month
in the Gregorian calendar
Month name origin
- name of the stars
বৈশাখ Bôishakh 30 / 31 31 গ্রীষ্ম (Grishshô)
April–May বিশাখা Bishakha
জ্যৈষ্ঠ Jyôishţhô 31 / 32 31 May–June জ্যেষ্ঠা Jyeshţha
আষাঢ় Ashaŗh 31 / 32 31 বর্ষা (Bôrsha)
Wet season/Monsoon
June–July উত্তরাষাঢ়া Uttôrashaŗha
শ্রাবণ Shrabôn 31 / 32 31 July–August শ্রবণা Shrôbôna
ভাদ্র Bhadrô 31 / 32 31 শরৎ (Shôrôt)
August–September পূর্বভাদ্রপদ Purbôbhadrôpôd
আশ্বিন Ashshin 31 / 30 30 September–October অশ্বিনী Oshshini
কার্তিক Kartik 29 / 30 30 হেমন্ত (Hemonto)
Dry season
October–November কৃত্তিকা Krittika
অগ্রহায়ণ Ôgrôhayôn 29 / 30 30 November–December মৃগশিরা (a.k.a. অগ্রহায়ণী) Mrigoshira(a.k.a. Ogrohayoni)
পৌষ Poush 29 / 30 30 শীত (Shīt)
December–January পুষ্যা Pushya
মাঘ Magh 29 / 30 30 January–February মঘা Môgha
ফাল্গুন Falgun 29 / 30 30 / 31 বসন্ত (Bôsôntô)
February–March উত্তরফাল্গুনী Uttorfalguni
চৈত্র Chôitrô 30 / 31 30 March–April চিত্রা Chitra


The Bengali Calendar incorporates the seven-day week as used by many other calendars. The names of the days of the week in the Bengali Calendar are based on the Navagraha (Bengali: নবগ্রহ nôbôgrôhô). The day begins and ends at sunrise in the Bengali calendar, unlike in the Gregorian calendar, where the day starts at midnight.

In the calendar originally introduced by Akbar in the year 1584 AD, each day of the month had a different name, but this was cumbersome, and his grandson Shah Jahan changed this to a 7-day week as in the Gregorian calendar, with the week also starting on a Sunday.[2]

Day name (Bengali) Romanization Divine figure/celestial body Day name (English)
রবিবার Rôbibar Robi/Sun Sunday
সোমবার Sombar Som/Moon Monday
মঙ্গলবার Mônggôlbar Mongol/Mars Tuesday
বুধবার Budhbar Budh/Mercury Wednesday
বৃহস্পতিবার Brihôspôtibar Brihospoti/Jupiter Thursday
শুক্রবার Shukrôbar Shukro/Venus Friday
শনিবার Shônibar Shoni/Saturn Saturday

Revised and non-revised versions

Differences shown between the two different versions of the Bengali calendar (for Asharh month of the year 1419). On the top is the "Traditional unrevised version" followed in West Bengal and below it is the "New revised version" followed in Bangladesh.


Pôhela Bôishakh in West Bengal and other states of India with Bengali diaspora, is celebrated on 14/15 April of the Gregorian calendar. However, according to the revised version of the calendar, now followed in Bangladesh, Pôhela Bôishakh always falls on 14 April. The length of the months are not fixed in the non-revised original sidereal calendar, now followed in India, rather is based on the true movement of the sun over the constellations of stars.On the contrary, length of the months are fixed in the revised version of the calendar, followed in Bangladesh.

Revised Bengali calendar

The Bengali calendar in Bangladesh was modified by a committee headed by Muhammad Shahidullah under the auspices of the Bangla Academy on 17 February 1966,[2] which was officially adopted by the government in 1987.

It is not clear; from what ground they start counting of 1st Bengali calendar year from the 593AD.

The length of a year is counted as 365 days, as in the Gregorian calendar. However, the actual time taken by the earth in its revolution around the sun is 365 days 5 hours 48 minutes and 47 seconds. To make up this discrepancy, the Gregorian calendar adds an extra day, to make a leap year, to the month of February every fourth year (except in years divisible by 100 but not by 400). To counter this discrepancy, and to make the Bengali calendar more precise, the following recommendations of the Bangla Academy are followed:


  1. 1 2 3 4 5 6 Kunal Chakrabarti; Shubhra Chakrabarti (2013). "Calendar". Historical Dictionary of the Bengalis. Scarecrow Press. pp. 114–5. ISBN 978-0-8108-8024-5.
  2. 1 2 3 4 5 Syed Ashraf Ali (2012). "Bangabda". In Sirajul Islam; Ahmed A. Jamal. Banglapedia: National Encyclopedia of Bangladesh (2nd ed.). Asiatic Society of Bangladesh.
  3. 1 2 3 Nitish K. Sengupta (2011). Land of Two Rivers: A History of Bengal from the Mahabharata to Mujib. Penguin Books India. pp. 96–98. ISBN 978-0-14-341678-4.
  4. 1 2 3 বাংলা বর্ষপঞ্জি - ইতিহাস BDnews blog
  5. 1 2 "Answering Islam: A Christian-Muslim Dialogue". Retrieved 14 November 2014.

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