Nanakshahi Calendar

Before 2003, Sikh festival dates were set by the Bikrami calendar, the lunisolar system shared across much of North India, which meant gurpurabs and other observances moved against the Gregorian calendar from year to year in the same way Diwali or Eid do. The Nanakshahi calendar was built to stop that drift for Sikh purposes specifically, fixing each month to a constant solar length so that, in principle, a festival such as Vaisakhi or a Guru's birth anniversary falls on the same Gregorian date every year rather than shifting with the moon.

The month names were kept from the Bikrami tradition, Chet, Vaisakh, Jeth and onward through Phaggan, so the change is one of mechanics rather than of vocabulary, and the calendar's epoch, year one, is set at 1469 CE, the birth year of Guru Nanak, giving the era its name. Vaisakhi anchors the whole structure: it is both the first day of the first month, Chet, and the historic anniversary of the founding of the Khalsa by Guru Gobind Singh in 1699, so the calendar's new year and one of Sikhism's most significant historical events fall on the same fixed date by design.

The calendar was designed by Pal Singh Purewal, a Canada based Sikh scholar, and adopted by the Shiromani Gurdwara Parbandhak Committee in 2003 as the official calendar for the historic gurdwaras it administers, including the Golden Temple at Amritsar, framed at the time as a marker of Sikh calendrical independence from the Bikrami system associated with Hindu practice. The reform did not hold unopposed.

A coalition of traditionalist bodies, the Sant Samaj among them, together with the Damdami Taksal, argued that several gurpurabs had always been reckoned by lunar tithis under the Bikrami calendar and should stay that way regardless of the new solar reform, and by 2009 they were pressing the case through the Shiromani Akali Dal, the political party aligned with the SGPC. Under that pressure the SGPC issued a revised version of the calendar in 2010, restoring Bikrami based dates for a number of festivals, including some Guru anniversaries and Bandi Chhor Divas, while retaining the fixed solar dating for Vaisakhi and the calendar's basic month structure. The result is that two documents both called the Nanakshahi calendar have circulated since 2010, the original 2003 design still published by Purewal and diaspora organisations that consider the revision a retreat, and the SGPC's amended 2010 version, alongside a third position that rejects the Nanakshahi reform altogether and keeps every Sikh date on the Bikrami calendar.