The lunar calendar Nepal Sambat (Nepal Bhasa: नेपाल सम्बत) is commonly used in the Kathmandu valley of Nepal. It is believed that in the reign of King Raghav Dev of Kathmandu, it was initiated by Sankhadhar Sakhwa to commemorate the pay back of all the debts of people living in Kathmandu, then known as "Ya." Local legend has it that he raised the funds through alchemy, turning the sand of the Bagmati River to gold dust. The Bikram Sambat is official calendar of Nepal. Gregorian calendar is also widely used due to it international acceptance and Nepal Sambat has its own special relevance for Newars living in Nepal. Nepal Sambat is one among few of the native calendars to Nepal. Most of others either passed over the time or only maintain existence in the religious calendars called Patro.

This calendar was widely used in official use during the Malla period in Kathmandu valley. After the unification of Nepal, Saka sambat took ground and later on, during the premiership of Chandra SJBR Bikram Sambat were recognized for official use. This calendar, Nepal sambat, is being revived, especially in Kathmandu valley, over the last 3 decades. Moreover, the calendar was widely used by Newars for cultural and religious purpose inside the Kathmandu because of its relation with festivals Jatra that are celebrated in Valley