The Indian national calendar (sometimes called Saka calendar) is the official civil calendar in use in India. It is used, alongside the Gregorian calendar, by The Gazette of India, news broadcasts by All India Radio, and calendars and communications issued by the Government of India. The term may also ambiguously refer to the Hindu calendar, and the Saka era is commonly used by different calendars as well.
The calendar was introduced by the Calendar Reform Committee in 1957, as part of the Indian Ephemeris and Nautical Almanac, which also contained other astronomical data, as well as timings and formulae for preparing Hindu religious calendars, in an attempt to harmonise this practice. Despite this effort, local variations based on older sources such as the Surya Siddhanta may still exist. Usage officially started at Chaitra 1, 1879 Saka Era, or March 22, 1957. However, government officials seem to largely ignore the New Year’s Day of this calendar in favour of the religious calendar.