Bikram Sambat Calendar — Complete Guide to Nepal's Date System
Nepal is one of the few countries in the world that uses its own official calendar system. The Bikram Sambat (विक्रम सम्बत्, abbreviated BS or B.S.) is the national calendar of Nepal, used for all government, legal, educational, and daily-life purposes. Every Nepali citizen interacts with this calendar from birth certificates to school exams to tax deadlines.
This guide covers everything you need to know about the Bikram Sambat calendar — its origins, structure, month names, how it compares to the Gregorian calendar, and how to convert between the two systems.
Origin and History of Bikram Sambat
The Bikram Sambat calendar is named after the legendary King Vikramaditya of Ujjain (in modern-day India), who is said to have established the era in 57 BCE after defeating the Shakas. The calendar counts years from this starting point, making BS year 1 equal to 57 BCE in the Gregorian system.
The calendar was widely used across the Indian subcontinent for centuries. While India officially adopted the Saka calendar (Shaka Samvat) after independence in 1947, Nepal retained the Bikram Sambat as its official calendar. King Prithvi Narayan Shah formalized its use during the unification of Nepal in the 18th century.
Today, the Bikram Sambat is deeply embedded in Nepali culture and governance. All government documents, official holidays, school schedules, fiscal years, and legal proceedings reference BS dates.
Bikram Sambat vs Gregorian Calendar Comparison
The most important thing to understand about BS is that it runs approximately 56 years and 8.5 months ahead of the Gregorian calendar. Here is a quick reference:
| Gregorian (AD) | Bikram Sambat (BS) | Difference |
|---|---|---|
| January 1, 2024 | Poush 16, 2080 | ~56.7 years |
| January 1, 2025 | Poush 17, 2081 | ~56.7 years |
| January 1, 2026 | Poush 17, 2082 | ~56.7 years |
| April 14, 2026 | Baisakh 1, 2083 (New Year) | ~56.7 years |
| January 1, 2027 | Poush 17, 2083 | ~56.7 years |
Note that the BS new year falls in mid-April (on or around April 14), not January 1. This means a single Gregorian year overlaps with parts of two BS years. For instance, January to mid-April 2026 falls in BS 2082, while mid-April onwards falls in BS 2083.
The 12 Months of Bikram Sambat
The BS calendar has 12 months. Unlike the Gregorian calendar where month lengths are fixed, BS month lengths vary each year because they are computed from actual astronomical solar transit times. Below are the months with their typical day ranges and approximate Gregorian equivalents:
| # | Nepali Name | Devanagari | Days (typical) | Gregorian Approx. |
|---|---|---|---|---|
| 1 | Baisakh | बैशाख | 30–31 | Apr–May |
| 2 | Jestha | जेठ | 31–32 | May–Jun |
| 3 | Ashadh | असार | 31–32 | Jun–Jul |
| 4 | Shrawan | साउन | 31–32 | Jul–Aug |
| 5 | Bhadra | भदौ | 31–32 | Aug–Sep |
| 6 | Ashwin | असोज | 30–31 | Sep–Oct |
| 7 | Kartik | कार्तिक | 29–30 | Oct–Nov |
| 8 | Mangsir | मंसिर | 29–30 | Nov–Dec |
| 9 | Poush | पुष | 29–30 | Dec–Jan |
| 10 | Magh | माघ | 29–30 | Jan–Feb |
| 11 | Falgun | फागुन | 29–30 | Feb–Mar |
| 12 | Chaitra | चैत | 30–31 | Mar–Apr |
A BS year has either 365 or 366 days, similar to the Gregorian leap year concept. However, the extra day is not added to a fixed month — instead, all month lengths are recalculated each year based on solar transit data.
How the Calendar Is Calculated
The Bikram Sambat is a lunisolar calendar, meaning it accounts for both the sun's position (solar months) and the moon's phases (for religious observances). The key astronomical principles are:
- Solar transit (Sankranti): Each month begins when the sun enters a new zodiac sign (rashi). The exact time of transit determines month length.
- Sidereal year: The calendar is based on the sidereal year (approximately 365.2564 days), which is the time for the sun to return to the same position relative to fixed stars.
- No fixed month lengths: Because solar transits do not occur at fixed intervals, month lengths vary from year to year, ranging from 29 to 32 days.
- Tithi system: Lunar phases (tithis) within each month determine auspicious dates for festivals, rituals, and ceremonies.
The Nepal Government publishes the official BS calendar (पात्रो, paatro) each year with the exact month lengths, festivals, and holidays calculated by the Nepal Panchanga Nirnayak Samiti (Calendar Determination Committee).
Major Festivals and Their BS Dates
Nepal's festivals follow the Bikram Sambat calendar. Here are the major festivals and their typical BS dates (exact tithi-based dates may shift by a day each year):
| Festival | Typical BS Month | Approximate AD Month | Significance |
|---|---|---|---|
| Nepali New Year | Baisakh 1 | Mid-April | Start of the BS year |
| Buddha Jayanti | Baisakh Purnima | May | Birth of Lord Buddha |
| Ropain (Rice Planting) | Ashadh 15 | Late June | Agricultural celebration |
| Janai Purnima / Raksha Bandhan | Shrawan Purnima | August | Sacred thread changing |
| Gaijatra | Bhadra 1 | August | Festival of cows |
| Krishna Janmashtami | Bhadra Krishna Ashtami | August–September | Birth of Lord Krishna |
| Teej | Bhadra Shukla Tritiya | September | Women's fasting festival |
| Dashain (Vijaya Dashami) | Ashwin Shukla Dashami | October | Biggest Nepali festival |
| Tihar (Deepawali) | Kartik Amavasya | October–November | Festival of lights |
| Chhath Parva | Kartik Shukla Shashthi | November | Sun worship |
| Maghe Sankranti | Magh 1 | Mid-January | Start of Magh, harvest festival |
| Maha Shivaratri | Falgun Krishna Chaturdashi | February–March | Lord Shiva's night |
| Holi (Fagu Purnima) | Falgun Purnima | March | Festival of colors |
| Ghode Jatra | Chaitra Krishna Ashtami | March–April | Horse racing festival |
Practical Usage in Daily Life
Understanding the BS calendar is essential for anyone living or working in Nepal. Here are the most common scenarios where you need BS dates:
- Birth date: All Nepali citizenship certificates record the birth date in BS. When applying for passports or visas, you may need to convert your BS birth date to AD.
- School calendar: The academic year starts in Baisakh (April) for government schools. Exams, holidays, and admissions follow BS dates.
- Tax deadlines: Nepal's fiscal year runs from Shrawan 1 to Ashadh end (mid-July to mid-July). Tax installments are due on Poush end and Chaitra end.
- Legal documents: All property registrations, contracts, and court documents use BS dates.
- Salary and payroll: Monthly salary cycles follow BS months.
Date Conversion Tools
Online Calculator Nepal provides several free tools to work with the Bikram Sambat calendar:
- Date Converter — Convert any date between BS and AD instantly.
- Nepali Calendar 2082 — View the full BS calendar with festivals, holidays, and events.
- Age Calculator (Nepali) — Calculate your exact age in BS years, months, and days.
- Nepali Date Today — See today's date in both BS and AD formats.
Historical Context: Why Nepal Uses a Different Calendar
While most countries adopted the Gregorian calendar during European colonization or through modernization efforts, Nepal — which was never colonized — retained its traditional calendar system. The Bikram Sambat has been in continuous use in the region for over two thousand years.
Nepal's decision to maintain BS reflects its cultural sovereignty and the deep connection between the calendar and religious observances. Hindu and Buddhist festivals are calculated based on lunar tithis within the BS framework, making a switch to the Gregorian calendar culturally impractical.
In practice, most Nepali people are comfortable with both calendars. The Gregorian calendar is used for international communication, airline tickets, and global business, while BS is used for everything domestic.