What is Bikram Sambat (BS)?

Bikram Sambat (BS), also written Vikram Samvat, is the official calendar of Nepal and the system used for almost all civil, legal and everyday timekeeping in the country — newspapers, government notices, school terms, birthdays, festival dates and the fiscal year are all reckoned in BS. Its year count runs roughly 56 years and 8½ months — about 56.7 years — ahead of the Gregorian (AD) calendar, so the BS year that began in April 2026 is 2083.

The calendar has twelve months, in order: Baisakh, Jestha, Ashadh, Shrawan, Bhadra, Ashwin, Kartik, Mangsir, Poush, Magh, Falgun and Chaitra. The year begins on the first day of Baisakh, which usually falls on 13–15 April in the Gregorian calendar and is celebrated as Nepali New Year. A full BS year is 365 or 366 days, the same length as a solar year.

Although it descends from an ancient Hindu lunisolar tradition, the version Nepal uses for civil purposes is effectively a solar calendar. The length of each month is fixed not by a simple repeating rule but by the sun's transit (Sankranti) through the signs of the sidereal zodiac, so individual months vary from 29 to 32 days and the same month can have a different number of days from one year to the next. Because the month lengths are determined astronomically and published in the official panchang (almanac) each year, accurate BS↔AD conversion relies on year-by-year lookup tables rather than a single arithmetic formula.

For a quick approximation, subtract about 57 from a BS year to get the Gregorian year, because the two calendars are nearly 57 years apart. More precisely, because the BS year starts in mid-April, you subtract 57 for the part of the BS year that falls before mid-April and 56 for the part after it. For example, BS 2083 runs from about 14 April 2026 to about 13 April 2027: dates in Baisakh–Chaitra 2083 up to the end of 2026 correspond to AD 2026 (2083 − 57 = 2026), while dates after the AD new year fall in 2027.

This mid-April offset is why simple subtraction gives the right year but never reliably gives the right month and day — the two new years are nearly four months apart, and BS month lengths differ from Gregorian ones. To convert an exact date such as a birthday or a deadline, Nepalis use a date converter or the official almanac rather than mental arithmetic.

The calendar governs Nepal's administrative life. The national fiscal year runs from the first day of Shrawan (about mid-July) to the end of Ashadh (about mid-July the following year), so budgets, tax filings and economic reports are all pegged to BS dates. Major Hindu festivals such as Dashain and Tihar, however, are set by the older lunar reckoning of tithis (lunar days) and so shift within the solar BS months from year to year.

The era takes its name from the legendary Indian king Vikramaditya of Ujjain and is traditionally said to commemorate his victory over invading Saka tribes; its epoch is placed at 57 BCE, which is the source of the roughly 57-year gap with the Gregorian calendar. Historians note that the actual term 'Vikrama Samvat' does not appear in the historical record until around the 9th century CE, so the attribution to Vikramaditya is part legend, but the 57 BCE epoch is the conventional starting point used throughout South Asia.

In Nepal the calendar was raised to the status of the official national calendar by the Rana administration around the turn of the 20th century — commonly dated to the period of Prime Minister Chandra Shumsher Rana, roughly 1901–1903 CE — when it was standardised for government and administrative use. It thereby displaced earlier systems, including the Shaka (Saka) era and the Newar Nepal Sambat, in official record-keeping.

Because Nepal's version evolved into a solar calendar tied to the sidereal zodiac, the modern BS calendar functions as a stable civil timekeeping system while still carrying its Hindu astronomical heritage. It remains, to this day, the calendar printed on government documents, citizenship records and the national almanac, alongside the Gregorian calendar used for international purposes.

Bikram Sambat is frequently confused with Nepal Sambat, but the two are distinct. Nepal Sambat is the lunisolar calendar of the Newar people of the Kathmandu Valley, with an epoch of 20 October 879 CE, traditionally credited to the merchant Shankhadhar Sakhwa; its year count is therefore only about 880 years ahead of the Gregorian calendar (roughly the 1140s in the 2020s), not nearly 57 years ahead like BS. Nepal Sambat was the official calendar of the Kathmandu Valley until the late 18th century and is today a recognised national calendar used ceremonially and in cultural contexts.

BS is also distinct from the Indian use of Vikram Samvat. India largely retains the traditional lunisolar form of Vikram Samvat for religious dates, in which an extra intercalary month (Adhik Maas) is inserted roughly seven times every nineteen years to keep the lunar months aligned with the seasons; Nepal, by contrast, uses the solar form for civil life, so it has no such leap month.

Other terms that often appear alongside Bikram Sambat include Sankranti (the sun's entry into a new zodiac sign, which marks the start of each BS month), tithi (the lunar day used to fix festival dates), the panchang or patro (the almanac that lists each year's exact month lengths and auspicious dates), and the Saka (Shaka) era, an older Indian epoch beginning in 78 CE that BS eventually replaced in Nepali official use.