The calendar is named after King Bikramaditya, an Indian emperor and started in the year 56 BC after Vikramaditya won a battle against the Sakas. The year count is approximatly 56 Years, 8 Months and 15 Days ahead of the Gregorian calendar. That approximates to 56.7 years. The first day of 2000 AD Gregorian was 17 Paush 2056 BS Nepali.
The Nepalese calendar is a luni-solar calendar which means that the relationship to the Gregorian calendar will vary slightly from year to year. The calendar year starts on the 13th or 14th of April (Gregorian) and comprises of 12 months. The months are named as follows: Baishakh, Jetha, Asar, Saun, Bhadau, Asoj, Kartik, Mangsir,Push, Magh, Phagun and Chait. Each month can vary in length by one day the shortest five months being 29 or 30 days and the longest four months being 31 or 32 days. The remaining 3 months are 30 or 31 days long.
The lengths of the months are set by astrologers who also decide the leap years. Leap years are created during the process of setting the lengths of the months. That is no special leap days are added.