Overview
The Bengali calendar, often called the Bangla calendar or Bônggabdô / Bangla Sôn, is a regional solar calendar used across Bengal and formally adopted as the national civil calendar of Bangladesh. Its New Year celebration, Pôhela Bôishakh, falls in mid-April and aligns with the start of the agricultural season. The equivalent date on the Western (Gregorian) calendar is generally 14 or 15 April, so the Bengali year differs from the Gregorian year by roughly 593 years depending on whether the date is before or after Pohela Boishakh; exact offsets vary with local practice and calendar reforms.
Structure and months
The calendar divides the year into twelve months that follow a solar cycle, and most modern Bengali civil variants use fixed month lengths so that the New Year is stable in mid-April. The months and their common romanized names are:
- Boishakh (Bôishakh)
- Joishtho (Joishtho)
- Ashar (Ashar)
- Srabon (Srabon)
- Bhadro (Bhadro)
- Ashwin (Ashwin)
- Kartik (Kartik)
- Agrahayan (Agrahayan)
- Poush (Poush)
- Magh (Magh)
- Falgun (Falgun)
- Chaitra (Chaitra)
In contemporary civil usage a few months have 31 days while most have 30; the month of Falgun sometimes gains an extra day in leap years in local variants. This arrangement keeps seasonal markers and festivals on consistent Gregorian dates.
Seasons
Traditional Bengali timekeeping recognizes six distinct seasons, each spanning two months. Starting at Pohela Boishakh, those seasons are: Grishmô (summer), Bôrsha (monsoon/rainy), Shôrôt (autumn), Hemôntô (dry season), Šhit (winter), and Bôsôntô (spring). These six-season divisions reflect agriculture, weather patterns and cultural life across Bengal and are often referenced in poetry and folk calendars.
History and development
The Bengali calendar evolved from older regional and Hindu solar-lunisolar timekeeping systems, later influenced by administrative reforms in medieval and early modern periods. A Mughal-era fiscal or harvest year known as the Fasli calendar affected the way months were counted for taxation and harvest cycles. Over time, local scholars and government committees proposed adjustments to fix month lengths and align the civil calendar with the Gregorian calendar for official use; several modern variants coexist across Bangladesh and Indian states with Bengali-speaking populations.
Uses, festivals and notable facts
Beyond civil administration, the Bengali calendar structures agricultural planning, religious and cultural festivals, and traditional markets. The mid‑April New Year, Pohela Bôishakh, is observed with fairs, cultural programs and special foods. The calendar also determines dates for harvest celebrations, seasonal observances and many regional holidays. Different communities—rural and urban, Bangladeshi and Indian—use slightly different versions, so festival dates and year numbers can vary by locality. For general reference and further reading see resources linked here: language and names, civil adoption, and New Year customs.
Variations and distinctions
Several distinct but related calendars exist in the Bengali cultural area: a traditional lunisolar ritual calendar used for some religious observances, a reformed civil solar calendar used for government and fiscal purposes, and regional practices maintained by communities. When consulting Bengali dates, note whether a source uses the traditional or the reformed civil version, since month lengths and year numbers may not match exactly across systems.