Bikram Sambat to Gregorian (AD): the complete guide

If you have a date written in Bikram Sambat (BS) and you need it in the Gregorian calendar (AD), or the other way around, the short answer is that there is no clean formula you can do in your head. The two calendars don't line up with a fixed offset, so the reliable way is to look the date up against the official Nepali calendar.

That gets you the answer in seconds. The rest of this guide explains why it isn't simpler, which matters the moment a converted date has to match a passport, a transcript, or a visa form exactly.

Why you can't just add a number

It's tempting to treat the gap as a constant. BS is "about 56 years and 8 to 9 months ahead" of AD, so why not add that and be done?

Two things break that approach:

• The year boundaries don't match. The BS year begins on 1 Baisakh,

which lands in mid-April on the Gregorian calendar. So for part of the year the gap is 56 years, and after the Nepali new year it becomes 57. A single offset is wrong for half the calendar.

• BS months change length. Gregorian months have fixed lengths (give or

take a leap day in February). Bikram Sambat months run anywhere from 29 to 32 days, and the pattern is not the same every year. The lengths come from astronomical calculations (the panchanga), not a repeating rule.

Add those together and any arithmetic shortcut drifts. It might be right for one date and a day off for the next, which is exactly the kind of error that gets a form rejected.

How the conversion actually works

Accurate BS ↔ AD conversion relies on a published table of how many days each BS month had, year by year. Once you know that, converting is just counting days forward from a known anchor.

The standard anchor is 1 Baisakh 2000 BS = 14 April 1943 AD. From there, the official Nepali panchanga records the length of every month through Chaitra 2099 BS (mid-April 2043 AD). That same table is what the Nepal government, printed patro calendars, and digital converters use for birth certificates, citizenship, and academic records. It's also why reliable conversion is limited to the 2000-2099 BS range. Outside it, the day-length data isn't defined.

The Nepali months, in order

BS has twelve months. Their approximate Gregorian span helps you sanity-check a converted date:

• Baisakh (बैशाख): mid-April to mid-May
• Jestha (जेठ): mid-May to mid-June
• Ashadh (असार): mid-June to mid-July
• Shrawan (साउन): mid-July to mid-August
• Bhadra (भदौ): mid-August to mid-September
• Ashwin (असोज): mid-September to mid-October
• Kartik (कार्तिक): mid-October to mid-November
• Mangsir (मंसिर): mid-November to mid-December
• Poush (पुष): mid-December to mid-January
• Magh (माघ): mid-January to mid-February
• Falgun (फागुन): mid-February to mid-March
• Chaitra (चैत): mid-March to mid-April

If a converter tells you that 1 Baisakh fell in, say, December, something is wrong. The new year is always mid-April.

A worked example

Take 1 Baisakh 2080 BS. That's the first day of the BS year 2080, so it's a Nepali new year. Converted, it is 14 April 2023 (Friday). Notice the gap here is 57 years (2080 minus 2023), because we're past the April boundary into the new BS year. That's a good reminder of why the "add 56" shortcut fails.

Where this trips people up

• Off-by-one from the boundary. A date in Chaitra (the last BS month) sits

just before the April rollover, so its AD year is one less than a date a few days later in Baisakh. Always trust the lookup, not the subtraction.

• Month-name spelling. "Ashadh" and "Asar", "Ashwin" and "Asoj" are the same

months under different romanizations. Match the Nepali script (असार, असोज) when in doubt.

• Out-of-range dates. Genealogy or historical dates before 2000 BS can't be

converted with the standard table.

Doing it accurately

For anything that has to match an official document, convert against the real calendar rather than estimating. If you're filling visa or admission forms, how to convert Nepali dates accurately walks through the common cases and the mistakes to avoid. And if your source date is trapped in an old Preeti-font document, you may also need to convert Preeti to Unicode before you can even read it correctly.

Key takeaways

• Bikram Sambat runs about 56 to 57 years ahead of the Gregorian (AD) calendar,

and the exact gap shifts at the mid-April new year.

• The BS year starts on 1 Baisakh, which falls in mid-April. For example,

1 Baisakh 2080 BS was 14 April 2023.

• BS month lengths vary from 29 to 32 days and change year to year, so no fixed

offset converts dates reliably.

• Accurate conversion uses the official panchanga day-length table, which covers

2000 to 2099 BS.

• For official documents, convert against the real calendar and record both the

BS and AD dates so they always match.