The Tamil calendar is a solar and sidereal Hindu calendar used in Tamil Nadu, India. It is also used in Puducherry, and by the Tamil population in Malaysia, Singapore, Mauritius and Sri Lanka. It is also used by Telugu speaking people in Tamil Nadu. It is used today for cultural, religious and agricultural events, with the Gregorian calendar largely used for official purposes both within and outside India. The Tamil calendar is based on the classical Hindu solar calendar also used in Assam, West Bengal, Kerala, Manipur, Nepal, Odisha, Rajasthan and Punjab.
There are several festivals based on the Tamil Hindu calendar. The Tamil New Year follows the nirayanam vernal equinox and generally falls on 14 April of the Gregorian year. 14 April marks the first day of the traditional Tamil calendar and this remains a public holiday in both Tamil Nadu and Sri Lanka. Tropical vernal equinox fall around 22 March, and adding 23 degrees of trepidation or oscillation to it, we get the Hindu sidereal or Nirayana Mesha Sankranti (Sun's transition into nirayana Aries). Hence, the Tamil calendar begins on the same date in April which is observed by most traditional calendars of the rest of India - Assam, Bengal, Kerala, Odisha, Manipur, Punjab etc. This also coincides with the traditional new year in Burma, Cambodia, Laos, Sri Lanka, Bangladesh Nepal and Thailand. The 60-year cycle is also very ancient and is observed by most traditional calendars of India and China, and is related to 5 revolutions of Jupiter according to popular belief, or to 60-year orbit of Nakshatras (stars) as mentioned in Surya Siddhanta.
The traditional Tamil year starts on 14 April 2013, Kaliyuga 5115. Vikrama and Shalivahana Saka eras are also used. There are several references in early Tamil literature to the April new year. Nakkirar, the author of the Nedunalvaadai writes in the 3rd century that the Sun travels from Mesha/Chitterai through 11 successive Raasis or signs of the zodiac. Kūdalūr Kizhaar in the 3rd century refers to Mesha Raasi/Chitterai as the commencement of the year in the Puranaanooru. The Tolkaapiyam is the oldest surviving Tamil grammar that divides the year into six seasons where Chitterai marks the start of the Ilavenil season or summer. The 8th century Silappadikaaram mentions the 12 Raasis or zodiac signs starting with Mesha/Chitterai. The Manimekalai alludes to the Hindu solar calendar as we know it today. Adiyaarkunalaar, an early medieval commentator or Urai-asiriyar, mentions the 12 months of the Tamil Hindu calendar with particular reference to Chitterai. There were subsequent inscriptional references in Pagan, Burma dated to the 11th century CE and in Sukhothai, Thailand dated to the 14th century CE to South Indian, often Vaishnavite, courtiers who were tasked with defining the traditional calendar that began in mid-April.
This list compiles the days of the week in the Tamil calendar:
|No.||Kizhamai (Tamil)||Weekday (English)||Vaasara (Sanskrit)||Lord or Planet||Gregorian Calendar equivalent|
For Tamils the each day begins at the sun rise.
The number of days in a month varies between 29 and 32.
The following list compiles the months of the Tamil Calendar.
|No.||Month (Tamil)||Month (English)||Sanskrit Name *||Gregorian Calendar equivalent|
|01.||சித்திரை||Cittirai||Chaitra||mid-April to mid-May|
|02.||வைகாசி||Vaikāci||Vaisākha||mid-May to mid-June|
|03.||ஆனி||Āni||Jyaishtha||mid-June to mid-July|
|04.||ஆடி||Āṭi||Āshāḍha||mid-July to mid-August|
|05.||ஆவணி||Āvaṇi||Shrāvaṇa||mid-August to mid-September|
|06.||புரட்டாசி||Puraṭṭāci||Bhādrapada/Prauṣṭhapada||mid-September to mid-October|
|07.||ஐப்பசி||Aippaci||Ashwina/Ashvayuja||mid-October to mid-November|
|08.||கார்த்திகை||Kārttikai||Kārttika||mid-November to mid-December|
|09.||மார்கழி||Mārkazhi||Mārgaṣīrṣa||mid-December to mid-January|
|10.||தை||Tai||Pausha/Taiṣya||mid-January to mid-February|
|11.||மாசி||Māci||Māgha||mid-February to mid-March|
|12.||பங்குனி||Paṅkuni||Phalguna||mid-March to mid-April|
The Tamil year, in keeping with the old Indic calendar, is divided into six seasons, each of which lasts two months:
|Season in Tamil||English Transliteration||English Translation||Season in Sanskrit||Season in English||Tamil Months||Gregorian Months|
|இளவேனில்||ila-venil||Light warmth||Vasanta||Spring||chithirai, vaigāsi||Mid Apr - Mid Jun|
|முதுவேனில்||mutu-venil||Harsh warmth||Grishma||Summer||āni, ādi||Mid Jun - Mid Aug|
|கார்||kār||Dark clouds, Rain||Varsha||Rainy||āvani, puratāci||Mid Aug - Mid Oct|
|குளிர்||kulir||Chill, Cold||Sharada||Autumn||aippasi, kārthigai||Mid Oct - Mid Dec|
|முன்பனி||mun-pani||Early dew||Hemanta||Early winter||mārkazhi, tai||Mid Dec - Mid Feb|
|பின்பனி||pin-pani||Late dew||Sishira||Late winter||māsi, panguni||Mid Feb - Mid Apr|
Sixty-year cycle 
The 60-year cycle of the Tamil calendar is common to North and South Indian traditional calendars, with the same name and sequence of years. Its earliest reference is to be found in Surya Siddhanta, which Varahamihirar (550 CE) believed to be the most accurate of the then current theories of astronomy. However, in the Surya Siddhantic list, the first year was Vijaya and not Prabhava as currently used. This 60-year cycle has also been adopted into the Chinese calendar.
After the completion of sixty years, the calendar starts a new with the first year. This corresponds to the Hindu "century." The Vakya or Tirukannitha Panchangam (the traditional Tamil almanac) outlines this sequence. It is related to the position of the planets in the sky with respect to earth. It means that the two major planets Sani/Saturn ( which takes 30 years to complete one cycle round the sun) and the Viyazhan/Jupiter (which takes 12 years to complete one cycle round the Sun) comes to the same position after 60 years.
The following list presents the current 60-year cycle of the Tamil calendar:
|No.||Name||Name (English)||Gregorian Year||No.||Name||Name (English)||Gregorian Year|
The months of the Tamil Calendar have great significance and are deeply rooted in the faith of the Tamil Hindus. Some months are considered very auspicious while a few are considered inauspicious as well.
Some of the celebrations for each month are listed below. Dates in parentheses are not exact and usually vary by a day or two. Underneath (or beside) the months of the Hindu calendar are their Gregorian counterparts.
|சித்திரை - Chithirai(April)||14 April - 14 May||Chitra Pournami & Varusha pirappu are the most important festivals in this month. Famous Chithirai thiruvizha is ceiebrated in Madurai Meenakshi Amman temple.|
|வைகாசி - Vaikaasi(May)||15 May - 14 June||Vaikaasi Visaakam is the most important day in this month.This month is most favorable month of Lord Subramainya (Murga Kadavul). Thirumangalam[Madurai] Shri Pathrakali Mariamman Temple 13day Vaigasi Festival starts at Sunday followed by vaigasi ammavasai[no moon day].|
|ஆனி - Aani(June)||15 June - 14 July||Aani Thirumanjanam or Aani Uttaram for Lord Nataraja is the most famous day in this month.|
|ஆடி - Aadi(July)||15 July - 14 August||A most important month for women. The most auspicious days are Fridays and Tuesdays in this month, these are called Aadi Velli and Aadi Chevvai and the Aadi Amavasya. Aadi Pooram is also a special day.18th day of adi is the most important day for the farmers (delta region) they prepare paddy seedlings.during this month "kanchi varthal" is famous in amman temples|
|ஆவணி - Aavani(August)||15 August - 15 September||An important month with many rituals. Brahmins change their sacred thread on Aavani Avittam. Each Sunday of the month is dedicated to prayers - Aavani Gnayiru.|
|புரட்டாசி - Purattaasi(September)||15 September - 15 October||An important month for Vaishnavas. Purattaasi Sani(Saturday) is an auspicious day for Lord Vishnu.|
|ஐப்பசி - Aippasi(October)||15 October - 14 November||The monsoons typically start over Tamil Nadu in this month. Hence the saying, "Aippasi Mazhai, adai mazhai" - meaning "Aippasi rains are persistent rains".
Also Annaabishekam for Lord Shiva is very famous in this month. The most famous Hindu festival "Deepavali" is celebrated in this month. The Fridays of this month - Aipassi velli - are dedicated to religious observance.
|கார்த்திகை - Karthikai(November)||15 November - 14 December||Another auspicious celebration for Shiva devotees is Thirukaarthigai. The Krithikaa Pournami is the special day of the full moon in the month of Kaarthikai, and the star is Krithikaa.
Each Monday of this month is dedicated to the worship of Lord Shiva. Every Monday is called "Somavaaram" when 108 or 1008 sangabhishekam are offered to Lord Shiva and Lord Muruga.
|மார்கழி - Maargazhi(December)||15 December - 14 January||This is another special month in the Tamil Calendar. Temples open earlier in the mornings and Devotees throng the temples early for puja and prasadam - the offering made to the deity which is later distributed to the devotees. Arudra Darisanam (Thiruvaadirai star in Tamil) is the most auspicious day in this month. This is also a very popular festival in Kerala, where it is called Thiruvaadira. The offering made to Lord siva is the Thiruvaadira Kali. Mukkodi Ekathesi is called "Paramapadha vaasal Thirappu" for Lord Vishnu. The Tiruvembaavai and Thirupaavai fast takes place in this month.|
|தை - Thai(January)
|15 January - 14 February||Pongal, which is the harvest festival, is celebrated on the first day of this month. Thai Friday is a popular day among Telugu speaking peoples settled in Tamil Nadu. Thaipusam is also a special day for Murugan devotees, who carry Kavadis to one of the Aarupadaiveedu (Literally meaning "six abodes").|
|மாசி - Maasi(February)||15 February - 14 March||Maasi Magam is the special day of which comes in this Month. Shivaratri is an important festival widely celebrated by Hindus in this month.|
|பங்குனி - Panguni(March)||15 March - 13 April||Panguni Uthiram, the last month of the year, is a famous festival and special to Murugan and Siva devotees.|
- The Hindus developed a system of calendrics that encapsulates vast periods of time. For computing the age of the earth and various geological and other epochs, as well as the age of mankind, they still employ a Tamil calendar derived from ancient astronomical data, known as the Tirukkanida Panchanga (cf. The Secret Doctrine, 2:49-51).
- This calendar contains a calculation of something over three hundred million years for the age of the present earth since sedimentation occurred, and a period of somewhat more than eighteen million years since the first appearance of our mankind.(?)
- The 10th Tamil month, called Thai, falls in mid-January each year. It is celebrated with much enthusiasm within the Tamil Community all over the world. Thai is marked by gifts of new clothing for family members and prayers to God for prosperity in the coming year. Thai and the fifth month Aavani are considered very auspicious for marriage and most marriages occur during these months.
- The fourth month Aadi is considered inauspicious, so weddings do not often fall in this month. Aadi is also the month of preparation for the next crop cycle by farmers. Therefore, farming communities avoid major events like weddings in this month. Those members of the Tamil community who don't actively contribute/participate in farming take advantage by having important functions like wedding in this month. For example, the business community prefers this month for weddings. Aadi is usually the worst month for business, although when businesses recently initiated Aadi discounts, this situation has changed significantly. Each Friday of this month is set aside for prayer and worship.
- Aadi is an inauspicious month for newlyweds to sleep together because a woman who conceives in this month will have a difficult delivery in May, the hottest month in Tamil Nadu (Agni natchathiram - ['pinezhu'] the last 7 days of Chithirai and ['munezhu'] the first 7 days of Vaigasi). 'Aadi' is also the windiest month in Tamil Nadu, and hence the phrase 'Aadi kaatru ammiyai nagatrum' (literally, 'the strong winds in the month of Aadi can even move a stone grinder')
- Purattaasi is when most of the non-vegetarian Tamil people fast from meat for a month. Each Saturday of this month is set apart to venerate the planet Saturn.
- Deepavali, is celebrated on the new moon day, in the seventh month Aipasi. The month of Aipasi is usually characterised by the North-East Monsoon in Tamil Nadu, which has given birth to a phrase, Aipasi adai mazhai meaning the "Non-stop downpour".
- Maargazhi falls in winter in Tamil Nadu, and is considered unauspicious for unmarried women to find a groom. The Shaivite fast of Thiru-vembaavai and the Vaishnava fast of Thiru-paavai are also observed in this month.
- The total number of days in a Tamil Calendar is an average 365 days and the days of the week are named similarly to those of the western calendar. The Vakiya Panchangam is employed for both sacred and civil calculations. The Trikanitha Panchangam is employed for astrological calculations.
The Tamil Calendar is so important to the life of Tamil-speaking people that most of the Festivals of Tamil Nadu are based on it. Some of Festivals include Tamil New Year or Puthandu in mid-April, Thai Pongal, Deepavali, Panguni Uthiram, Thirukaarthigai, Aadiperukku, Navaratri etc.
See also 
- Lines 160 to 162 of the Nedunalvaadai
- Poem 229 of Puranaanooru
- Professor Vaiyapuri Pillai, 'History of Tamil Language and Literature' Chennai, 1956 page 35, 151
- Canto 26 of Silappadikaaram. Canto 5 also describes the foremost festival in the Chola country - the Indra Vizha celebrated in Chitterai
- G.H. Luce, Old Burma - Early Pagan, Locust Valley, New York, Page 68, and A.B. Griswold, 'Towards a History of Sukhodaya Art, Bangkok 1967, pages 12-32
- Tamil Calendar 2012 @ tamildailycalendar.in
-  @ Tamil Calendar for all past and future years (தமிழ் நாள்காட்டி)