5 Different Calendars of India

A Hindu calendar/Image Credit: Library of Congress
A calendar is a system of organizing days for different social and administrative purpose. It is done by periodizing the time into days, weeks, months and years. A calendar also mean a list of planned events.

In India, there are three different systems of Calendars being used. These are
1. Solar Calendar System
2. Lunar Calendar System
3. Luni-Solar Calendar System

Solar Calendar System
A solar calendar system closely corresponds to the time taken by the Earth in its one revolution around the Sun. It consists 365 days and divided between 12 months.

Lunar Calendar System
Similar to a solar year, a lunar year consists of 12 months (lunations). However it consists, approximately 354 days which roughly translates into 29.26 to 29.80 days in a month. Consquently a lunar year is 11 days shorter than a solar year and an intercalary is month is introduced every 2.7 years to adjust the difference. This intercalary month is known as Adhik Masa or Mala Masa. Furthermore, a rare correction is made over the cycle of a few centuries where a month is dropped. It is known as Kshaya month. It occurs due to the complexities of lunar year solar year and earth year.

Luni-Solar Calendar System
In a luni-solar calendar system, year is calculated on the basis of solar cycle whereas months are calculated on the basis of lunar cycles. The adjustment between to two systems is brought by intercalations and suppression. Most of the Hindu calendars are Luni-Solar Calendars.

Shukla and Krishna Paksha
In Hindu Calendars, a month is also divided into two Pakshas. These are Shukla Paksha and Krishna Paksha. The Shukla Paksha corresponds to the waxing phase of moon between new moon and full moon whereas the Krishna Paksha corresponds to the wanning phase of the moon between full moon and new moon.

List of Calendars used in India.
Saka Calendar
Also known as Shalivahana Shaka calendar, Saka calendar is the national calendar of India. It is used alongside Georgian Calendar by The Gazette of India and other communications issued by the Government of India since 1957. Intrestingly, it is also used in Java and Bali among Indonesian Hindus. It was started by the Sakas to mark their victory over the Kushans. Its zero year correponds to 78 AD. The names of the months in Saka Calendar are

Chhaitra (March 21 – April 20)
Vaishakha (April 21-May 21)
Jyeshtha (May 22-June 21)
Ashadha (June 22- July 22)
Shravana (July 23-August 22)
Bhaadra (August 22-September 22)
Ashwin (September 23-October 22)
Kartika (October 23-November 21)
Agrahayana (November 22-December 21)
Pausha (December 22-January 20)
Magha (January 21- February 19) and
Phalguna (February 20-March 20/21)

Vikrami Calendar
Vikram Samvat or Vikrami Calendar is ancient luni-solar Hindu calendar established by Vikramaditya of Ujjain after defeating Sakas. It is adopted as the national calendar by Nepal. Its zero year corresponds to 56 BC. However, many historians believe that it was originally instituted by the Chandragupta Vikramditya of Malawa Ganarajya around 400 AD. Henceforth, it is also known in the pantheons of archaeology as the Malawa Gana Era.

Bengali Calendar
The Bengali Samvat or Bengali calendar is mainly used by Bengalis around the world. It is a luni-solar calendar and its zero year corresponds to 593/594 CE. It was adopted as the national calendar by the Government of Bangladesh in 1987. Interestinly, Chaitra, the first month in Saka Calendar is the last month in Bengali Calendar. The months in a Bengali Samvat are

Boisakh
Jyoistho
Asharh
Sharbon
Bhadro
Ashshin
Kartik
Ograhayon
Poush
Magh
Falgun
Choitro

Hijri calendar
The Muslim Calendar, also known as Hijri Calendar, is a lunar calendar used by the Muslim community all over the world to determine proper days of Islamic religious observations. It is divided into 12 months in a year of 354/355 days. Its zero year is 622 AD corresponding the death of Prophet Mohammad. The first and the ninth of the Hijri calendar are considered sacred. Muslims observe a full month fast during the ninth month of Ramadan for the purification of souls. The 12 months of the Hijri calendar

Muharram
Safar
Rabi’ al-awwal (Rabi’ I)
Rabi’ al-thani (Rabi’ II)
Jumada al-awwal (Jumada I)
Jumada al-thani (Jumada II)
Rajab
Sha’ban
Ramadan
Shawwal
Dhu al-Qi’dah
Dhu al-Hijjah

Georgian Calendar

The Georgian Calendar came to India with the European colonizers. It is a solar calendar having 365 days divided into 12 months. An extra day is added every four years in the month of February to adjust the dates of calendar with the Earth year (365.25 days).