BS ⇄ AD
A Bikram Sambat converter that works for any year. Most converters ship a table of month lengths and stop working where the table ends. This one computes each month's start from the sun's position, the same way a panchang does.
- Days in month
- 30
- Sankranti (NPT)
- 18 Oct 2026, 10:25
- Margin to day boundary
- 626 min
Festivals
How it works
A BS month starts at a sankranti, when the sun enters the next sidereal zodiac sign. The sun is modelled with the Surya Siddhanta, and the start date follows the traditional rules: the date in Nepal the sankranti falls on, except that a Shrawan sankranti before sunrise counts for the previous day and a Magh sankranti after sunset counts for the next day.
Checked against two published datasets for 1975–2083 BS, it matches about 99% of months. Every miss is a sankranti within a few minutes of a day boundary, and those months are flagged here. Future years aren't officially published yet, so no converter can guarantee them.
Festivals like Dashain and Tihar follow the moon instead. Each is fixed to a tithi (lunar day) in a lunar month, and falls on the day that tithi is current at the time the festival is observed: sunrise for most, midday for Bhai Tika, evening for Laxmi Puja. Leap months (adhik maas) are detected too, which is why Dashain sometimes moves to late October. These match every festival in Hamro Patro's official 2082–2083 lists.