The National Calendar of India, adopted in 1957, is based on the:

The National Calendar of India, adopted on 22 March 1957, is based on the Saka era, which began in 78 CE.

About the National Calendar:

• It was adopted on the recommendation of the Calendar Reform Committee, set up in 1952 under the chairmanship of the scientist Meghnad Saha.
• It came into use from 1 Chaitra 1879 Saka era, which corresponded to 22 March 1957.
• It is used, along with the Gregorian calendar, for official purposes, such as the Gazette of India, news broadcasts by All India Radio, and calendars and communications issued by the Government of India.

Features of the National Calendar:

• It is a solar calendar with 365 days in a normal year and 366 days in a leap year.
• The year begins on 1 Chaitra, which falls on 22 March in a normal year and 21 March in a leap year.
• It has 12 months: Chaitra, Vaishakha, Jyeshtha, Ashadha, Shravana, Bhadra, Ashvin, Kartika, Agrahayana, Pausha, Magha and Phalguna.
• Chaitra has 30 days (31 in a leap year); the months Vaishakha to Bhadra have 31 days each; the remaining months have 30 days each.
• The dates of the National Calendar have a permanent correspondence with the Gregorian calendar.
• The Saka year is 78 years behind the Gregorian year (for dates from January to March, 79 years).

About the Saka era:

• It begins from 78 CE.
• Many scholars believe it was started by the Kushana king Kanishka, while others link it with the Shaka rulers of western India.
• It was widely used in inscriptions, especially in western and southern India.

Other eras:

• "Vikram era": begins in 57 BCE; used in north and west India and in Nepal.
• "Gupta era": begins in 319-320 CE.
• "Hijri era": the Islamic calendar, which begins in 622 CE (the Hijra of Prophet Muhammad); it is a lunar calendar.
• "Kali era": begins in 3102 BCE.

Why not the other options?

• ✗The Vikram era is used for religious purposes in many parts of India.
• ✗The Gupta era was used in ancient times.
• ✗The Hijri era is the Islamic calendar.