AD to BS Converter Online Free

Nepal runs on two calendars at once. Official documents, land records, citizenship certificates, school certificates and the national newspapers are dated in Bikram Sambat (BS), the country’s official calendar — while passports, international tickets, computers and most of the rest of the world use the Gregorian calendar (AD). Anyone who lives, works, studies or travels in Nepal converts between the two constantly: a date of birth recorded as 17 Poush 2079 on a certificate must be written as 1 January 2023 on a passport form; a wedding fixed for 1 Jestha 2080 must be told to foreign guests as 15 May 2023. The AD to BS converter at the top of this page performs the conversion in both directions, in your browser: pick a Gregorian date and read its Bikram Sambat equivalent with the Nepali month name and weekday, or type a BS date and read the AD date it falls on. Nothing is uploaded to a server.

The conversion cannot be done with a simple formula, and understanding why is understanding the Nepali calendar itself. Bikram Sambat months have between 29 and 32 days, and the length of any given month changes from year to year in a pattern fixed by official publication, not by arithmetic. Jestha has 32 days in one year and 31 in another; Mangsir may have 29. So every honest converter works the way this one does: it counts days from a fixed anchor that both calendars agree on — 1 Baishakh 2000 BS fell on 14 April 1943 AD — and walks through the official published month-length table, year by year and month by month, until the count lands on your date. The table embedded in this converter covers every BS year from 2000 to 2099, the same reference table standard Nepali date converters use, and the result is exact: not an estimate, not an offset, but a day-for-day conversion verified against documented reference dates, three of which are worked through below.

The Bikram Sambat Calendar in Brief

Bikram Sambat is a solar calendar that runs about 56 years and 8 months ahead of the Gregorian calendar — which is why the BS year 2080 began in April 2023 AD, and why the quick mental shortcut “add 56 or 57” gets the year roughly right and the day almost always wrong. The BS year begins in mid-April with Baishakh and runs through twelve months: Baishakh, Jestha, Ashad, Shrawan, Bhadra, Ashwin, Kartik, Mangsir, Poush, Magh, Falgun and Chaitra. Unlike Gregorian months, whose lengths every schoolchild memorises once, BS month lengths are set for each year by Nepal’s calendar committee and published in official calendars (patros); a month of the same name can be 29, 30, 31 or 32 days depending on the year. Most years total 365 days and some 366, but not by a leap-year rule you can compute — the table is the authority.

That irregularity is precisely why a converter must be a table lookup rather than a formula. Between 1 Baishakh 2000 BS and your date there are a specific number of days, and the only way to know how they distribute across months and years is to add up the published lengths. This tool does exactly that addition with integer day counts, in both directions, so an AD date and its BS equivalent always describe the same single day — convert forth and back and you return to the date you started with, for every one of the 36,525 days the table covers. Weekdays need no table at all: the weekday belongs to the day itself, so the converter reads it from the Gregorian date with standard calendar arithmetic, and it is the same weekday in both calendars.

How to Use the Converter

The tool works in both directions, and each direction takes a few seconds.

To convert AD to BS:

1. Click the date box in the “AD to BS” row and pick the Gregorian date (live test: 1 January 2023).
2. Press “Convert AD to BS”.
3. Read the headline line: the same day written in both calendars, with the Nepali month name — for the live test, “1 January 2023 AD = 17 Poush 2079 BS”.
4. Read the line beneath for the numeric form (2023-01-01 AD = 2079-09-17 BS), the weekday (Sunday), and how many days the BS month has that year.

To convert BS to AD:

1. Type the BS year (2000 to 2099), choose the BS month from the list, and type the day of the month.
2. Press “Convert BS to AD”.
3. Read the headline line — for example, 17 Poush 2079 BS comes back as 1 January 2023 AD — and the numeric line with the weekday underneath.

If a date falls outside the covered range (BS 2000–2099, which is AD 14 April 1943 to 13 April 2043), or a BS day number is larger than that month has in that year, the tool says so plainly instead of printing a wrong date.

Worked Examples

Example 1: 1 January 2023 AD — New Year’s Day

Converting 1 January 2023 gives 17 Poush 2079 BS, a Sunday. This is one of the standard documented reference conversions for the Nepali calendar, and it is easy to sanity-check the shape of the answer: January sits in the middle of the BS year, roughly eight and a half months after Baishakh, so a Poush date (month 9) is exactly where a January date should land; and the BS year is 2079 rather than 2080 because the BS new year does not arrive until mid-April. The detail line adds that Poush has 30 days in 2079 BS — the kind of fact that matters when the converted date will be written onto a form.

Example 2: 15 May 2023 AD — the first of Jestha

Converting 15 May 2023 gives 1 Jestha 2080 BS, a Monday — another documented reference conversion, and a tidy one: the date is the very first day of a BS month, so it makes a strong test of any converter (an off-by-one error anywhere in the table walk would move it to 30 Baishakh or 2 Jestha). By mid-May the BS year has already turned to 2080, which began on 14 April 2023 — a date you can verify with the same tool by converting 14 April 2023 and watching it return 1 Baishakh 2080.

Example 3: 20 June 2017 AD — a certificate date

Converting 20 June 2017 gives 6 Ashad 2074 BS, a Tuesday — the third documented reference conversion used to verify this tool, and the most typical real-world case: an ordinary mid-year date of the kind printed on citizenship and academic certificates in Nepal, which must be rendered into AD for foreign universities, employers and embassies. Converting it back — 6 Ashad 2074 BS into the BS-to-AD side of the tool — returns 20 June 2017 exactly, as every date in this converter does: the two directions are the same day-count walked forwards and backwards, so a round trip can never drift.

Example 4: The edges of the table — 14 April 1943 and 13 April 2043

The converter’s range anchors are themselves worth testing. 14 April 1943 AD converts to 1 Baishakh 2000 BS, the first day of the table; 13 April 2043 AD converts to 30 Chaitra 2099 BS, its last day. One day earlier than the first (13 April 1943) or one day later than the last (14 April 2043) and the tool declines, with a message naming the covered range. A hundred years of dates covers the birth dates, certificate dates and planning dates of essentially every living user — and where a historical date before 1943 is needed, a converter with an older table, not a guess, is the right tool.

How to Read the Output

The headline line states the equivalence in words: day, month name and year in both calendars. Words are the safest form for anything that will be copied by a person, because “17 Poush 2079” cannot be misread the way a bare numeric date can — in numeric form the same date is 2079-09-17 in BS year-month-day order, and confusing the month number (9 = Poush) or the order is the classic transcription error. The line beneath gives exactly that numeric form for both calendars, the weekday, and — on the AD-to-BS side — the number of days in the resulting BS month that year. Check the weekday as a free audit: if you know from a diary or a photo’s timestamp that the day was a Sunday, a converted date claiming Wednesday has gone wrong somewhere. Check the month-day against the month’s length too, when a document gives you both: a certificate reading “32 Ashad” is possible (Ashad has 32 days in some years) while “32 Poush” is impossible in every year, because Poush never has more than 30.

Where AD–BS Conversion Is Used

Inside Nepal, the conversion is daily administrative life. Dates of birth exist in BS on citizenship certificates and in AD on passports, and the two must agree exactly when either is renewed or used abroad — a one-day mismatch between a birth certificate and a passport application is a real and common bureaucratic problem, and it almost always traces back to a converter or a clerk using an approximate offset. Land and property documents (Lal Purja) are dated in BS; bank loans, insurance policies and court filings move between the calendars; schools record admissions in BS and report to international bodies in AD. Nepali festivals and observances — Dashain, Tihar and the rest — are fixed in the BS calendar (some by lunar tithi rather than the solar date, a separate matter no date converter settles), so their AD dates change every year and are looked up constantly. Outside Nepal, the Nepali diaspora converts for the same reasons in reverse: a parent’s BS birth date for a visa form, a marriage date for a certificate, a land transaction back home. In all of these the requirement is the same — an exact, table-based conversion, which is what this tool provides, in both directions, for a hundred years of dates.

Common Mistakes

The first common mistake is the year shortcut: adding 56 or 57 to the AD year gives a plausible BS year and a wrong date, because the calendars do not merely differ in year numbers — their months start on different days and have different, irregular lengths. The second is trusting converters that use a fixed day offset (some old tools assume BS is always exactly 56 years, 8 months and some days ahead); such a converter can be right for a stretch of dates and silently wrong after a month whose length it guessed badly, which is why documented reference dates — like the three in the examples — matter when choosing a tool. The third is a numeric-order mix-up: writing a BS date as day/month/year into a form expecting year/month/day, or reading the BS month number as a Gregorian month. The fourth is assuming a BS month has the same length as last year — Jestha 2080 has 32 days in this table while other years give it 31 — so recurring dates such as monthly payments or anniversaries must be converted year by year, not carried over. The fifth is forgetting the range: dates before 14 April 1943 AD belong to BS years before 2000 and need a different table; this tool refuses them rather than extrapolating, and any converter that cheerfully converts them from a 2000–2099 table is inventing answers.

Limits: What This Tool Does and Does Not Do

This converter converts single dates between the Gregorian (AD) and Bikram Sambat (BS) calendars, in both directions, for BS years 2000–2099 — AD 14 April 1943 to 13 April 2043 — using the official published month-length table for those years and the anchor 1 Baishakh 2000 BS = 14 April 1943 AD. It reports the month name, numeric form and weekday with every conversion, and it validates BS day numbers against the actual length of the chosen month in the chosen year. It does not convert dates outside that range, and it does not handle the lunar (tithi-based) dates used for religious observances, which follow a different reckoning. It does not convert to or from other calendar systems (such as Hijri or the Nepali fiscal-year conventions used in accounting), and it converts one date at a time rather than batches. A note on sources, stated plainly: for BS years 2000–2083 all widely used published tables agree day-for-day; a few library tables differ in the far tail (2084 onward), where this tool follows the internally consistent standard reference table — every year 365 or 366 days — whose conversions round-trip exactly across the whole range and reproduce the documented reference dates. Within its range and scope, the conversions are exact day counts, and the three worked examples let you verify that yourself before trusting it with a certificate.

Privacy: Your Date Stays in Your Browser

A date of birth is identity data — half of a login, a line on every certificate, a fact people are rightly careful with. Every date you convert with this AD to BS converter stays in your browser: the day-counting runs locally, nothing is sent to a server, nothing is stored, and there is no account. Closing the page clears the tool. This browser-only design is the same principle behind the other free tools on Your Smart Kit, and for a converter whose most common input is a birth date, it is the only design that makes sense.

Frequently Asked Questions

How does the converter work without a formula?

Because there is no formula to use. Bikram Sambat month lengths are published per year by Nepal’s calendar authorities and vary irregularly between 29 and 32 days. The converter counts days from an anchor both calendars agree on — 1 Baishakh 2000 BS = 14 April 1943 AD — and walks the published table month by month. That is how all accurate AD–BS converters work, and it is why their answers agree with the printed patro.

Why is the BS year sometimes 56 and sometimes 57 years ahead?

The BS calendar is about 56 years and 8 months ahead of AD. From mid-April (the BS new year) to December, the difference in year numbers is 57; from January to mid-April it is 56. That is why 1 January 2023 is still 2079 BS, while 15 May 2023 is already 2080 BS.

What range of dates does it cover?

BS years 2000 to 2099, which is AD 14 April 1943 to 13 April 2043 — 36,525 days. That covers the birth dates on the certificates of essentially everyone alive, plus a generation of planning ahead. Dates outside the range are refused with a message rather than guessed.

Can I convert a date of birth for a passport or visa form?

Yes — that is the most common use, and it is exactly what the worked examples demonstrate: a BS birth date from a citizenship certificate converts to the AD date the form wants, with the weekday as a cross-check. Do compare the result against any other document you hold; if two sources disagree, a table-based conversion like this one, checked against the reference examples, is the one to trust.

Does it also give the weekday?

Yes, both directions report the weekday, and it is the same in both calendars because it belongs to the day itself. It is a genuinely useful check — many people remember the weekday of a birth or a wedding even when the date has been copied wrongly somewhere.

Is the date I enter uploaded or saved?

No. The conversion runs entirely in your browser from the embedded table; nothing is sent to a server, stored, or shared.

Related Tools on Your Smart Kit

If you found the AD to BS converter useful, the other date tools on Your Smart Kit cover the neighbouring jobs. The English Date converter writes any date out in its British, American, ordinal and numeric forms — handy when a converted date must be written in words on a form. The DOB Converter is built for dates of birth specifically, giving every written form plus the weekday of birth, exact age and days lived. The Date Calculator counts days between two dates and adds or subtracts days, and the Age Calculator works out an exact age from a birth date. Each runs in your browser, free, with no sign-up. Try the converter at the top of this page with the three reference dates first — 1 January 2023, 15 May 2023 and 20 June 2017 — and when it returns 17 Poush 2079, 1 Jestha 2080 and 6 Ashad 2074, you can trust it with your own dates.