A Bikram Sambat month lasts as long as the Sun takes to cross one sidereal sign. It can be 29 to 32 days long, and the same month can have a different length each year. The tables below give the real month lengths for this BS year and the next, with the AD date each month starts and ends on.
39 gazetted public holidays this year, Saturdays not counted. Holidays →
Bikram Sambat is a solar calendar. Baisakh begins when the Sun enters Mesh (sidereal Aries) and ends when it enters Brisha. Every other month follows the same rule. The Earth's orbit is an ellipse, so the Sun's apparent speed changes through the year. It crosses some signs in a little over 29 days and others in a little over 31. This is why months run from 29 to 32 days. The count also changes from year to year because the time the Sun enters a sign shifts a little each year. A month that ended a few hours before midnight one year can end a few hours after midnight the next year, which adds a day.
Compared with the Gregorian calendar
Gregorian month lengths are fixed by rule. January always has 31 days, and February gets an extra day in years divisible by four. A BS month has no fixed length. Its length depends on the Sun's position. Because of this, no formula converts BS to AD correctly for every date, and converters that use a formula are off by a day on some dates. A correct conversion needs the published month-length table for that year. This site uses those tables.
Years of 365 and 366 days
A BS year is one full circuit of the Sun, so it has 365 or 366 days. It follows the sidereal year, which is about twenty minutes longer than the tropical year used by the Gregorian calendar. The extra day has no fixed place like 29 February. It goes to whichever month has its sankranti pushed past midnight, and that can be any month. In a 366-day BS year, one month is a day longer than usual, and which month it is changes from year to year.
Adhik maas belongs to the lunar calendar
Adhik maas is the extra month added roughly every three years. It is part of the lunar calendar that festivals follow. It is not part of the solar Bikram Sambat months on a wall calendar, and a BS year never has thirteen months. Adhik maas changes festival dates. Dashain and Tihar fall on lunar tithis, so their BS dates shift by a couple of weeks from one year to the next, and more in an adhik maas year. BS month lengths are not affected.
Reading the table
Each row shows how many days (gate) the month has and the AD dates of its first and last day. The first date is the sankranti day. When checking a document, use these two AD dates to see which BS month a date falls in.
Common questions
How many days are in a Nepali month?
Between 29 and 32, depending on the month and the year. The table above gives the exact count for the current BS year and the next one.
Which Nepali month is the longest?
Usually Ashadh, which often has 32 days because the Sun appears to move slowest at that time of year. Jestha and Shrawan have 31 or 32. The shortest are typically Mangsir, Poush and Magh at 29 or 30.
Does Bikram Sambat have a leap year?
It has years of 366 days, but no leap-day rule. The extra day goes to whichever month the sankranti timing pushes over. There is no fixed leap month and nothing like 29 February.
Can I work out the AD date by subtracting 56 years and 8 months?
Only roughly. BS runs 57 years ahead from Baisakh 1 to 31 December (mid-Poush) and 56 years ahead from 1 January to the end of Chaitra, and the day-of-month rarely lines up because the months are different lengths. Use the converter for an exact date.
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