To convert a BS to AD date, subtract 57 from the Bikram Sambat year for dates from Baisakh to about mid-Poush, and subtract 56 for dates from about mid-Poush to Chaitra. That gives you the right year. For the exact day you need a year-by-year conversion table or a date converter, because BS month lengths change every year.
Most people in Nepal need this for paperwork. Citizenship certificates, school records and birth certificates use BS dates, while visa forms, foreign job applications and university applications abroad ask for the AD date. The two dates must match exactly on every document.
What Is the Difference Between BS and AD?
Bikram Sambat (BS) runs about 56 years and 8.5 months ahead of the Gregorian (AD) calendar. The year 2026 AD overlaps with 2082 and 2083 BS. Both are solar calendars. A BS month starts when the sun enters a new sidereal sign, so its length varies from year to year. AD months have fixed lengths. This is the one difference that makes conversion hard.
BS has 12 months, from Baisakh to Chaitra, and the new year starts in mid-April, not on 1 January. For the month list, see the 12 Nepali calendar months in order. For the calendar's history, read what the Bikram Sambat calendar is.
Why Is the Offset About 56.7 Years?
Bikram Sambat counts from 57 BC, the traditional start of King Vikramaditya's era. AD counts from year 1. That head start of about 57 years is still there today. Because the BS new year falls in mid-April, the difference between the year numbers changes partway through each AD year.
The time gap between the two calendars stays at about 56 years and 8.5 months. That is where the figure about 56.7 years comes from. What changes is the difference between the year numbers. From January to mid-April the BS year has not changed yet, so the BS year is the AD year plus 56. From Baisakh 1 (mid-April) it is the AD year plus 57.
| Period in 2026 AD | Corresponding BS year | Year difference |
|---|---|---|
| 1 Jan to mid-April 2026 | 2082 BS | BS year = AD + 56 |
| Mid-April to 31 Dec 2026 | 2083 BS | BS year = AD + 57 |
Why Doesn't a Fixed Formula Work?
A fixed formula fails because BS month lengths are not constant. In AD, April always has 30 days and July always has 31. A Bikram Sambat month can have 29, 30, 31 or 32 days, and the count changes from year to year. Adding a set number of days will not reliably give you the right AD date.
Variable month lengths
The length of each BS month depends on when the sun moves from one zodiac sign to the next (sankranti). There is no repeating pattern. Baisakh can have 31 days one year and 30 or 32 in another. For this reason conversion tables are calculated and published year by year, and converter software uses stored month-length data for each year.
The quick estimate and its limits
For a quick estimate, subtract 57 from the BS year (56 for dates from about mid-Poush to Chaitra). Then assume each BS month starts around the middle of an AD month: Baisakh around 14 April, Shrawan around 17 July, and so on. This usually gets you within a few days. For a passport, a contract or an exam form, a few days off is not acceptable. Use an exact lookup.
How to Convert BS to AD: Worked Examples
Use a verified conversion table or converter, not arithmetic alone. Take a birth date of 2050 Baisakh 1 BS. Subtracting 57 from the year points to mid-April 1993, but it does not tell you whether Baisakh 1 fell on 13 or 14 April that year. The exact answer is 13 April 1993 AD, and only a table confirms it.
Example: BS to AD
Start with the BS date, for example 2080 Mangsir 15.
A quick estimate puts it in late November or early December 2023.
The exact date is 1 December 2023 AD. Check the table to get the exact day.
Example: AD to BS
Start with the AD date, for example 15 August 2026.
It is after mid-April, so add 57 to the year: 2083 BS.
The exact date is 30 Shrawan 2083 BS. The day of the month never lines up one to one, so check the day as well as the year.
The Easiest Accurate Way to Convert
Use a date converter that stores the month lengths for each BS year. The Katigate date converter converts BS to AD and AD to BS without any manual calculation, and it gives the correct day even across month changes, where the quick formula often slips by a day or two.
Katigate also shows the daily panchang, rashifal, festival dates and auspicious saait, all using the same BS-to-AD date data. You can open the calendar and converter from the Katigate home page, and our guide to the Nepali Calendar app lists all the features.
Bikram Sambat is not the only calendar era used in Nepal. If a date matches neither BS nor AD, it may be in Nepal Sambat. See Bikram Sambat vs Nepal Sambat vs AD to tell them apart.
Check the year boundary and leap day
Two checks illustrate why a fixed year offset is insufficient. In Katigate’s conversion data, 1 January 2026 is Poush 17, 2082, while 14 April 2026 is Baisakh 1, 2083. Gregorian leap day, 29 February 2024, is Falgun 17, 2080.
Enter the full date in the converter, note which calendar you entered, then convert the result back. This round trip checks entry consistency within the same tool; it is not independent proof of an official record. For an application, compare the result with the date already recorded on the relevant document and ask the receiving office about discrepancies.
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Frequently Asked Questions
How many years ahead is BS from AD?
Bikram Sambat is about 56 years and 8.5 months ahead of the Gregorian AD calendar, usually rounded to 56.7 years. The BS new year falls in mid-April, so from January to mid-April the BS year is the AD year plus 56, and after that it is the AD year plus 57.
Can I convert BS to AD with a simple formula?
You can estimate the year by subtracting 57 from the BS year (56 for dates from about mid-Poush to Chaitra), but the day will not always be right. BS months vary between 29 and 32 days from year to year, so no fixed formula gives every date correctly. For official documents, check with a date converter or published table.
Why is my converted date off by a day or two?
A one or two day error almost always comes from using the average offset instead of the actual month lengths for that year. BS month lengths change every year, so only a converter that stores the month data for each year gives the exact day. Manual subtraction is often off.
What is the BS year for 2026 AD?
Most of 2026 AD falls in 2083 BS. January to mid-April 2026 is still 2082 BS. The year changes on Baisakh 1, the Nepali new year in mid-April. Because of this, check the day and month before adding 57 to the year.