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The Bangla Calendar (Bengali: বঙ্গাব্দ Bônggabdo or বাংলা সন Bangla Shôn) or Bangla calendar may refer to the sidereal solar used by the Bangla people in their calendar officially used in Bangladesh. The year begins on Pohela Boishakh, which falls on 14 April according to the tropical calendar in Bangladesh.

The current Bangla year is Template:BANGLAYEAR. The Bangla year is 594 less than the AD or CE year in the Gregorian year if it is before Pôhela Boishakh, or 593 less after Pôhela Boishakh.

History[link]

Bangabda Bangla calendar, also known as 'Bangla Sal', was promulgated by the Mughal emperor Akbar in 1584 AD. The new calendar was initially known as Tarikh-e-Elahi and was introduced on 10 or 11 March 1584. Though the new calendar was promulgated in the twenty-ninth year of Akbar's reign, it dates from his ascension to the throne on 5 November 1556.

The purpose of Tarikh-e-Elahi was to glorify Akbar's ascent to the throne as well as to facilitate the collection of revenue. The Mughal emperors had been using the Hijri calendar for the purposes of collecting revenue. However, as Abul Fazl explains in Akbar Namah, the use of the Hijri calendar was irksome to the peasantry because there was a difference of 11 or 12 days between the lunar and the solar years, with 31 lunar years being equal to 30 solar years. Revenue was collected according to the lunar year, whereas the harvest was dependent on the solar one. From the beginning of his reign, Akbar had felt the need of introducing a uniform, scientific, and workable system of calculating days and months through a reformed calendar. With this end in view, he commissioned Amir Fathullah Shirazi, a distinguished scientist and astronomer, to make the changes.

Accordingly, the first of muharram 963 AH was also made the starting point of 963 of Tarikh-e-Elahi. Since the month of Muharram 963 AH coincided with the month of Baishakh, the month of Baisakh was made the first month of the new era instead of the month of Chaitra which was the first month of the shakabda, then being used in Bengal.

During the four hundred odd years that have elapsed since the Tarikh-e-Elahi was promulgated, a difference of 14 years has arisen between the Hijri and Bangla calendars. The Islamic Hijri calendar is a lunar calendar while the Bangla calendar is a solar one. The lunar year is 11 days shorter than the solar year. Hence the difference that has arisen between the Hijri calendar and the Bangla one: 2002 is 1408 of the Bangla year but 1422 of the Hijri year. The difference between the Bangla year and the Gregorian year, both of which are solar years, has remained the same. At the time of the introduction of the Tarikhe-e-Elahi, the difference between the Gregorian and Hijri years was 1556-963=593 years, and the difference in 2002 remains the same: 2002-1409=593 years.

During the reign of Akbar, each day of the month used to have a different name. As it was cumbersome to memorise the 31 names of the days of the month, Akbar's grandson, shahjahan, brought it down to a weekly system in his fasli san (agricultural calendar). His seven days of the week are similar to the week in the western calendar, with the Bangla week also starting from Sunday. 1 Rabi for Sun (Sunday) 2 Som for Moon (Monday) 3 Mangal for Mars (Tuesday, or Tiwes Daeg, the day of Tiw, Mars, the god of war) 4 Budh for Mercury (Wednesday) 5 Brihaspati for Jupiter (Thursday) 6 Shukra for Venus (Friday) 7 Shani for Saturn (Saturday).

The names of the months of the year were also changed. The months of the year were initially known as Farwardin, Khordad, Teer, Murdad, Shahrivar, Aban, Azar, Dey, Bahman etc. It is not known why the months were given the names Baisakh, Jyaistha, etc, but it is presumed that the names were derived from the Shakabda which had been introduced in 78 AD to commemorate the reign of the Saka Dynasty. The names of the months, as derived from different stars, were as follows: 1 Baishakh from Vishakha (Librae) 2 Jyaistha from Jaistha (Scorpii) 3 Asadh from Asadha (Sagittarii) 4 Shravan from Shravana (Aquilae) 5 Bhadra from Bhadrapada (Pegasi) 6 Ashvin from Ashvini (Arietis) 7 Kartik from Krttika (Tauri) 8 Agrahayan from Agraihani (Aldebaran) 9 Paus from Pusya (Cancri) 10 Magh from Magha (Regulus) 11 Falgun from Falguni (Leonis) 12 Chaitra from Chitra (Virginis)

The length of a year in the Bangla calendar, as in the Gregorian calendar, is counted as 365 days. 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 the month of February every fourth year (except in century years not divisible by 400). The Bangla year did not take into account these extra hours. Bangla months too were of different lengths. In order to counter this discrepancy and make the Bangla calendar more precise, a committee to reform the Bangla calendar was set up on 17 February 1966 under the auspices of the bangla academy and under the guidance of muhammad shahidullah. Under the recommendations of the committee, the months from Baisakh to Bhadra were to be counted as of 31 days each, while the months from Asvin to Chaitra were to be considered as of 30 days, with Chaitra having 31 days every four years. According to the popular hypotheses about the beginning of Bengali calendar, Mughal Emperor Akbar, who ruled from 1556 CE until 1605 CE, and one of his councilors Fatehullah Shirazi are credited with introducing the new Bengali calendar for tax collection purposes. Before the introduction of the Bengali calendar, during Muslim rule in India agricultural and land taxes were collected according to the Islamic Hijri calendar. However, as the Hijri Calendar is a lunar calendar, the agricultural year did not always coincide with the fiscal year. Therefore, farmers were hard-pressed to pay taxes out of season. In order to streamline tax collection, Emperor Akbar ordered a reform of the calendar. Accordingly, Amir Fatehullah Shirazi, a renowned scholar of the time and the royal astronomer, formulated a new calendar based on the lunar Hijri and solar Hindu calendars. The resulting Bangla calendar was introduced following the harvesting season when the peasantry would be in a relatively sound financial position. In keeping with the harvesting season, this new calendar initially came to be known as the Harvest Calendar, or ফসলী সন Fôsholi Shôn. During the reign of the Mughals, the Bengali Calendar was officially implemented throughout the empire. The month-names continued to be as per Hindu-astrological nomenclature. Akbar did not start the Bengali calendar with a value 1, but instead jump-started it with the then existing [Hijri calendar] value.^[1]

Another study suggests, Bengali calendar actually might have started with a value one during the reign of King Shashaanka of ancient Bengal, who ruled approximately between 590 CE and 625 CE. The king is credited with starting the Bengali era.^[2] His kingdom encompassed West Bengal, Bangladesh and parts of Bihar, Orissa and Assam. The starting point of the Bengali era is estimated to be on Monday, 12 April 593 in the Julian Calendar and Monday, 14 April 593 in the proleptic Gregorian calendar. The Bengali calendar is derived from the Hindu]. solar calendar, which is itself based on the [[Surya Siddhanta]

Organization[link]

Seasons[link]

The Bengali calendar consists of 6 seasons, with two months comprising each season. Beginning from Pohela Boishakh, they are Grishsho (গ্রীষ্ম) or Summer; Bôrsha (বর্ষা) or Rainy/Monsoon season; Shôrot (শরৎ) or Autumn; Hemonto (হেমন্ত) or the Dry season; Šit (শীত) or Winter; and Bôshonto (বসন্ত) or Spring. But as the traditional calendar used in India is sidereal, it 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 reformed tropical version of the calendar used in Bangladesh will continue to maintain the seasons as mentioned above.

Months[link]

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The names of the twelve months of the Bengali calendar are based on the names of the নক্ষত্র nokkhotro (lunar mansions): locations of the moon with respect to particular stars during the lunar cycle. These names were derived from the Surya Siddhanta, an ancient Indian book on Astronomy. The names of the months are:

• বৈশাখ Boishakh after the star, বিশাখা Bishakha
• জ্যৈষ্ঠ Joishţho after the star, জ্যেষ্ঠা Jeshţha
• আষাঢ় Ashaŗh after the star, উত্তরাষাঢ়া Uttorashaŗha
• শ্রাবণ Srabon after the star, শ্রবণা Srobona
• ভাদ্র Bhadro after the star, পূর্বভাদ্রপদ Purbobhadropôd
• আশ্বিন Ashshin after the star, অশ্বিনী Ôshshini
• কার্তিক Kartik after the star, কৃত্তিকা Krittika
• অগ্রহায়ণ(মার্গশীর্ষ) Ôgrohaeon after the star, মৃগশিরা Mrigoshira
• পৌষ Poush after the star, পুষ্যা Pushsha
• মাঘ Magh after the star মঘা Môgha
• ফাল্গুন Falgun after the star, উত্তরফাল্গুনী Uttorfalguni
• চৈত্র Choitro after the star, চিত্রা Chitra

Names and approximate lengths of Bengali months :^[3]

Days[link]

The Bengali Calendar incorporates the seven-day week as used by many other calendars. Also like other calendars, the names of the days of the week in the Bengali Calendar are based on celestial objects, or নবগ্রহ nôbogroho.

• Monday: সোমবার Shombar after সোম Shom (a Lord Shiva or Moon)
• Tuesday: মঙ্গলবার Monggolbar after মঙ্গল Monggol (planet Mars)
• Wednesday: বুধবার Budhbar after বুধ Budh (planet Mercury)
• Thursday: বৃহস্পতিবার Brihoshpotibar after বৃহস্পতি Brihoshpoti (planet Jupiter)
• Friday: শুক্রবার Shukrobar after শুক্র Shukro (planet Venus)
• Saturday: শনিবার Shonibar after শনি Shoni (planet Saturn)
• Sunday: রবিবার Robibar after রবি Robi (Sun)

In the Bengali calendar, the day begins and ends at sunrise, unlike in the Gregorian calendar, where the day starts at midnight.

Revised Bengali calendar[link]

The Bengali calendar in Bangladesh (then East Pakistan) was modified by a committee headed by Muhammad Shahidullah under the auspices of the Bangla Academy on 17 February 1966.

The length of a year in the Bengali calendar, as in the Gregorian calendar, is counted as 365 days. 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). The Bengali calendar, which was based on astronomical calculations, did not make this extra leap year adjustment. Bengali months, too, were of different lengths. To counter this discrepancy, and to make the Bengali calendar more precise, the following recommendations of the Bangla Academy are followed:

• The first five months of the year from Boishakh to Bhadro will consist of 31 days each.
• The remaining seven months of the year from Ashshin to Choitro will consist of 30 days each.
• In every leap year of the Gregorian calendar, an additional day will be added in the month of Falgun, which is just 14 days after 29 February. (Modified without material change).

The revised calendar was officially adopted in Bangladesh in 1987. However, it is not followed in the neighbouring state of West Bengal, India, where the traditional calendar continues to be followed due to the deep bond of Hindu culture with the Bengali calendar. Hindu religious festivals are celebrated based on a particular lunar day and Bengali calendar combination.

Revised and non-revised versions[link]

The first of Boishakh, Pôhela Boishakh, is the Bengali New Year's Day. In West Bengal, it is celebrated on 14/15 April. However, since the calendar was revised in Bangladesh the new year now always falls on 14 April.

In West Bengal, India, the Bengalis follow a sidereal solar calendar unlike the Tropical year solar calendars, such as the revised Bengali and Gregorian Calendars. The mathematical difference between the sidereal and the tropical calendars accounts for the difference of starting the new year in Bangladesh and West Bengal, India. Because of this the length of the months are also not fixed in the Bengali sidereal calendar, but rather are based on the true movement of the sun.

Leap year[link]

Although the sidereal solar calendar is followed in West Bengal, India, the number of days in the months are determined by the true motion of the Sun through the zodiac. In this calendar, seven is subtracted from the year, and the result is divided by 39. If after the division the remainder (= (year  - 7) / 39) is zero or is evenly divisible by 4, the year is then designated as a leap year and contains 366 days, with the last month, Choitro, taking 31 days. There are 10 leap years in every 39 years, although an extraordinary revision may be required over a long time.^{[citation needed]}

According to the new calendar system in Bangladesh, Falgun (which begins mid-February) has 31 days every four years. To keep pace with the Gregorian calendar, the Bengali leap years are those whose corresponding Gregorian calendar year is counted as a leap year. For example, Falgun 1410 was considered a Bengali leap month, as it fell during the Gregorian leap month of February 2004.

Usage[link]

The usage and popularity of the Bengali calendar in eastern South Asia is partly due to its adaptation to the unique seasonal patterns of the region. Eastern South Asia has a climate that is best divided into six seasons, including the monsoon or rainy season and the dry season in addition to spring, summer, fall, and winter.

In everyday use, the Bengali Calendar has been largely replaced by the Gregorian Calendar in Bengali-speaking regions, although it is still essential for marking holidays specific to Bengali culture (e.g. Pôhela Boishakh, Durga Puja, etc.), and for marking the seasons of the year. The Bengali calendar is recognized by the government of Bangladesh, whose offices date all their correspondence with the Bengali date as well as the Gregorian one. Almost every Bengali- and English-language newspaper in Bangladesh and West Bengal prints the day's date according to the Bengali Calendar alongside the corresponding date of the Gregorian Calendar. Many newspapers in Bangladesh also add a third date, following the Islamic Hijri Calendar. Thus, it is quite common in Bangladesh to find the date written three times (e.g. "15 Falgun 1412, 17 Muharram 1427, 27 February 2006") under the newspaper title.

Related calendars[link]

The Bengali calendar is related to the Hindu solar calendar, which is itself based on the Surya Siddhanta. The Hindu solar calendar also starts in mid-April, and the first day of the calendar is celebrated as the traditional New Year in Mithila,Assam, Kerala, Manipur, Nepal, Orissa, Punjab, Tamil Nadu, and Tripura in addition to Indian state of West Bengal and Bangladesh. Nepal, Thailand and Sri Lanka also celebrate new year around the same time (12–15 April). This is also known as Mesha Shong-kronti.

Footnotes[link]

1. ^ page-331 to page-333, The Argumentative Indian, Author: Amartya Sen, ISBN 0-14-101211-0
2. ^ Majumdar, Ramesh C. (1943). The History of Bengal. Dacca. pp. 58–68. ISBN 81-7646-237-3. 
3. ^ According to the unrevised calendar used in India

External links[link]

• Downloadable Software(free): Gregorian (English) to Bangla Date Converter for forever
• Bengali calendar according to Vishuddha Siddhanta Panjika (বাংলা ক্যালেন্ডার)
• Online Bangla Date Converter
• Bangla Date Converter with VB 6.0 Source Code
• Online English Date to Bangla Date Converter
• Bangla Date Converter written in Visual Basic
• Bangla Calendar: The Origin of Bangla new year and celebrating Pahela Baishakh
• Reconstructed Bengali Calendar as used in Bangladesh (বাংলা ক্যালেণ্ডার)
• Wordpress Plugin for Bangla Calendar
• The Bengali Calendar: A proud possession by M. Arshad Ali
• Hindu Panchangam calendars for the world
• Bangla Panjika for 2000 years (বঙ্গাব্দ ১-২০০০ সাল) according to Surya Siddhanta
• Bangla Panjikas according to Surya Siddhanta