The Fascinating History of the Bikram Sambat (BS) Calendar
If you look at an official Nepali document, you might feel like you've time-traveled into the future. That’s because Nepal uses the Bikram Sambat (BS) calendar as its official national calendar, which is approximately 56 years and 8.5 months ahead of the globally recognized Gregorian (AD) calendar.
Who Was Emperor Vikramaditya?
The calendar derives its name from the legendary Emperor Vikramaditya of Ujjain, India. According to historical tradition, King Vikramaditya established the "Vikrama" era in 57 BCE to commemorate his victory over the invading Saka (Scythian) forces.
Though its origins are deeply rooted in ancient India, the Bikram Sambat calendar was officially adopted by the Rana rulers of Nepal in 1901 AD (1958 BS), cementing its status as the heartbeat of Nepalese civic and religious life.
How the Calendar Works
Unlike the Gregorian calendar, which is strictly solar and features fixed month lengths (with the exception of leap years), the Bikram Sambat calendar is a solar-lunar hybrid. The length of a month is determined by the time it takes the sun to transition from one zodiac sign (Rashi) to the next.
Because the Earth's orbit is elliptical, the sun's speed appears to vary. This means a Nepali month like Baisakh (the first month) or Kartik can be 29, 30, 31, or even 32 days long, and this fluctuates from year to year.
The Importance of the Panchanga
Because of this astronomical variability, the calendar cannot be mathematically projected indefinitely with simple formulas. Every year, a group of elite astrologers and mathematicians known as the Nepal Panchanga Nirnayak Samiti calculates the exact solar and lunar positions to release the official "Patro" (Calendar) for the upcoming year.
This variability is exactly why translating dates between BS and AD is so complex, necessitating the use of our specialized BS to AD Date Converter.