[1][2] It is a lunisolar calendar, using twelve to thirteen lunar months each solar sidereal years.
[3] In colonial scholarship, the era was believed to be based on the commemoration of King Vikramaditya expelling the Sakas from Ujjain.
[4] According to popular tradition, King Vikramaditya of Ujjain established the Vikrama Samvat era after defeating the Śakas.
Despite heavy odds but aided by miracles, the Śaka king defeated Gandharvasena and made him a captive.
His son, Vikramaditya, being brought up in the forest, had to rule from Pratishthana (modern Paithan in Maharashtra).
This inscription, from the Chauhana ruler Chandamahasena, was found at Dholpur and is dated "Vikrama Samvat 898, Vaishakha Shukla 2, Chanda" (20 April 842).
V. A. Smith and D. R. Bhandarkar believed that Chandragupta II adopted the title of Vikramaditya, and changed the era's name to "Vikrama Samvat".
[10] One of several regional Hindu calendars in use on the Indian subcontinent, it is based on twelve synodic lunar months and 365 solar days.
During British colonial rule of the Indian subcontinent, the Gregorian calendar was adopted and is commonly used in urban areas of India.
In 2003, the India-based Sikh Shiromani Gurdwara Parbandhak Committee controversially adopted the Nanakshahi calendar.
The Rana dynasty of Nepal made the Bikram Sambat the official Hindu calendar in 1901 CE, which began as 1958 BS.
In India, the reformulated Saka calendar is officially used (except for computing dates of the traditional festivals).
The waxing phase, beginning with the day after the new moon (amavasya), is called gaura or shukla paksha (the bright or auspicious fortnight).
The waning phase is called krishna or vadhya paksha (the dark fortnight, considered inauspicious).