Bikram Sambat vs Gregorian: How Nepal's Calendar Really Works
If you have ever filled a Nepali government form, you have met the Bikram Sambat (BS) calendar — and probably paused, unsure how it relates to the year on your phone. Nepal is one of the few countries whose official, legal calendar is not the Gregorian one. Here is how it works and why converting dates is trickier than adding a fixed number.
Why Nepal is ~57 years "ahead"
Bikram Sambat begins its count in 57 BCE by Gregorian reckoning, traditionally linked to King Vikramaditya. So the BS year is roughly 56 years and 8–9 months ahead of the AD (Gregorian) year. As of mid-2025 AD, the BS year is 2082. That offset is not a clean 57 years, which is the first reason you cannot just add a constant.
The real complication: irregular months
The Gregorian calendar is fixed: January always has 31 days, April always 30. Bikram Sambat is a solar calendar based on astronomical calculations, and its month lengths change from year to year, ranging from 29 to 32 days. The month of Jestha might have 31 days one year and 32 the next.
This is why software cannot compute BS↔AD with a formula. It needs verified lookup tables of how many days each BS month had in each year. Good converters (like the AD↔BS date converter) ship tables covering roughly 2000 BS to 2100 BS, and accuracy is only guaranteed inside that range.
The twelve months
| BS month | Approx. Gregorian period |
|---|---|
| Baisakh | mid-Apr – mid-May |
| Jestha | mid-May – mid-Jun |
| Ashadh | mid-Jun – mid-Jul |
| Shrawan | mid-Jul – mid-Aug |
| Bhadra | mid-Aug – mid-Sep |
| Ashwin | mid-Sep – mid-Oct |
| Kartik | mid-Oct – mid-Nov |
| Mangsir | mid-Nov – mid-Dec |
| Poush | mid-Dec – mid-Jan |
| Magh | mid-Jan – mid-Feb |
| Falgun | mid-Feb – mid-Mar |
| Chaitra | mid-Mar – mid-Apr |
The Nepali new year, Baisakh 1, falls around April 13–14. Because BS months straddle the middle of Gregorian months, a single BS date almost always maps to two different Gregorian months.
Where it matters in daily life
- The fiscal year. Nepal's fiscal year runs Shrawan 1 to Ashadh end — roughly mid-July to mid-July. Tax slabs, budgets, and salaries are all referenced to the BS fiscal year (e.g., FY 2082/83).
- Official documents. Citizenship, land records, contracts, and bank forms use BS dates.
- Festivals. Dashain and Tihar move on the Gregorian calendar precisely because they are fixed on the lunar/BS system.
Converting accurately
To convert, you cannot count days with a formula — you look up the cumulative day counts in the BS tables and map to the Gregorian calendar. For everyday needs, use a tool with verified tables rather than an approximation. If you also need to know the gap between two dates in either calendar, the Date Difference Calculator counts the exact days.
The takeaway
Bikram Sambat is not "Gregorian plus 57." It is a living solar calendar with year-by-year irregular months, which is exactly why conversion is a table lookup, not arithmetic. Understand that, and the calendar stops being mysterious — you just need a reliable converter and an awareness that the fiscal year and festivals march to the BS beat.