Bikram Sambat: why Nepal's calendar is 57 years ahead

Nepal doesn't use the Gregorian calendar. It runs on Bikram Sambat (बिक्रम सम्बत), whose year number sits about 56 years and 8½ months in front of the Gregorian count. That gap turns out to be the least interesting thing about it. BS months start on their own days, run anywhere between 29 and 32 days, and don't keep the same length from one year to the next.

The short answer

Take the Gregorian year and add 56 or 57. Which one depends on where the date falls, because the Nepali year turns in April rather than January:

• 1 Jan – 13 Apr add 56
• 14 Apr – 31 Dec add 57

The step happens on Nepali New Year, Baisakh 1. Before it, the Gregorian year has already rolled over and the Nepali one hasn't caught up; after it, both have moved.

Both halves of 2026 show it. In January it was Magh 2082 (2026 + 56). By July it was Shrawan 2083 (2026 + 57). The Gregorian year never changed; the Nepali one did.

Where the era comes from

The era takes its name from Vikramaditya, a king of Ujjain who by tradition started the count around 57 BCE after beating the Shakas. That version of events comes from a Jain text, the Kalakacharyakatha.

Historians are careful with that story. Vikramaditya sits somewhere between history and folklore, and Britannica notes that some scholars hand the era to the Scytho-Parthian ruler Azes instead. Even the start year isn't settled: you'll see it written as 57 BCE and as 58 BC depending on the source. For centuries the same era went by another name entirely, the Malava era.

None of that unsettles the calendar itself. The count has run unbroken whatever its origin, which is what puts it 56 to 57 years above the Gregorian year today.

The same era survives in parts of India as Vikram Samvat. Nepal is the only country that actually runs its government on it. Court records, land deeds, school terms, contracts, newspaper mastheads: all BS. Gregorian dates get printed alongside for anything international.

How it became official

Nepal made Bikram Sambat its official calendar in 1901, or 1958 BS, under the Rana prime minister Chandra Shumsher.

Older reckonings didn't vanish. Nepal Sambat is still kept by Newars, Tamu Losar by Gurungs, Sonam Losar by Tamangs. Each has its own new year, and several are public holidays.

Solar, not lunar

Almost everyone assumes Bikram Sambat is a lunar calendar. It isn't.

Nepal's version is sidereal solar. A month lasts exactly as long as the sun spends in one sign of the zodiac, and it ends at sankranti, the moment the sun crosses into the next one. (India's Vikram Samvat is lunisolar, and several states there open the year in autumn. Same era, different machinery.)

Festivals run on a third system. Most are set by the moon, so Dashain and Tihar slide around the BS calendar every year while Nepali New Year stays fixed on Baisakh 1.

Why the months change length

Gregorian month lengths are just a rule somebody wrote down. February has 28 days because we say so.

A BS month has no such rule. It lasts however long the sun takes to cross one zodiac sign, and that isn't constant, because Earth's orbit is an ellipse. By Kepler's second law we move fastest in early January near perihelion and slowest in early July near aphelion. The sun appears to sprint through the winter signs and crawl through the summer ones.

So Jestha and Ashadh stretch to 31 or 32 days. Poush and Magh shrink to 29 or 30. And because the sankranti moment rarely lands tidily at midnight in Kathmandu, a month that ran 32 days last year can come back at 31.

The table below is generated from this site's own calendar data, not typed by hand:

There's no formula behind any of it. You can compute a Gregorian calendar from scratch; a BS calendar has to be read off astronomical tables. That causes a problem people hit constantly.

Why date converters disagree

Convert a date in 2085 BS using three different Nepali calendar tools and you can get three answers.

Past years are fine. Everyone agrees on what already happened. Future years are predictions, and the published panchang revises them as the calculations get refined. Any software library that shipped its dataset a few years ago is still handing out the old numbers.

There's an official arbiter, at least. The Nepal Panchanga Nirnayak Samiti, which sits under the Ministry of Culture, Tourism and Civil Aviation, is the body that settles the national panchanga and approves the calendars allowed to publish from it.

This bit us while building this site. Two widely used date-conversion packages had the wrong month lengths for 2084 and 2085 BS, and one of them had 2085 starting on the wrong weekday altogether. So every month boundary published here, 2082 through 2085 BS, is validated against the official panchanga rather than taken from a library.

Nepali New Year

The year turns on Baisakh 1, which falls on the 13th or 14th of April. That's when the sun enters Aries, and the country takes the day off.

It's also why the 56/57 offset flips when it does. And if you've ever seen a Nepali passport or certificate with a birth year that looks impossible, that's the explanation. It's counted 56 or 57 years higher.