TheTamil calendar is asiderealsolar calendar used by theTamil people.^[1][2] It is used in theIndian subcontinent, and other countries with significant Tamil population likeSri Lanka,Malaysia,Singapore,Myanmar andMauritius. It is used in contemporary times for cultural, religious and agricultural events, with theGregorian calendar largely used for official purposes.^[3]

There are several references to the calendar in earlyTamil literature.Nakkeerar, theSangam period author of theNeṭunalvāṭai, wrote in the third century CE that the Sun travels each year fromMesha/Chittirai in mid-April through 11 successive signs of the zodiac.^[4] The same is referenced to by Kūdalūr Kiḻar inPuṟanāṉūṟu.^[5][6]Tolkappiyam, the oldest surviving Tamil grammar text, divides the year into six seasons and Chittirai marks the start of the "ilavenil" (summer) season.^[7] The fifth century CE treatise ofCilappatikaram mentions the 12rāśis (zodiac signs) that correspond to the Tamil months.^[8] The sixth century epicManimekalai alludes to this to thhe Hindu solar calendar.^[9]

Inscriptional evidences fromPagan in Myanmar from the 11th century CE and inSukhothai in Thailand from the 14th century CE point to South Indian courtiers being tasked with defining the traditional calendar that followed a similar cycle.^[10][11]

The Tamil calendar is based on the Hindu system of calendrics that was used to calculate date and time.^[12] TheTirukkanidaPanchanga derived from astronomical data is used as a basis for the same.^[13] The calendar is similar to traditional calendars followed in other parts of theIndian subcontinent, andSoutheast Asia.^[14]

The Tamil calendar follows a 60-year cycle similar to the other traditional calendars of India.^[15] TheTamil New Year follows theNirayana system, and usually falls on 13 or 14 April in theGregorian year.^[16] The new year starts on the date arrived by adding the days corresponding to the 23 degrees of trepidation (oscillation) to thevernal equinox, when the Sun begins its transition as per the Hindu sidereal calendar.^{[17][page needed]} A Tamil calendar year might consist of 365 or 366 days in a year.^[18]

The 60-year cycle is common to Hindu traditional calendars, with similar names and sequence of years. The earliest reference of the same is inSurya Siddhanta, dated between 4th and 9th century CE. There are parallels to thesexagenary cycle used in theChinese calendar,^[19][20][21] though which influenced the other has been subject to debate.^[22]

After the completion of a cycle of sixty years, the calendar re-starts with the first year of a new cycle.^[23] As per the HinduPanchangam, it represents the year in whichShaniSaturn (which takes 30 years to complete one cycle round the Sun) andVyalan (Jupiter) (which takes 12 years to complete one cycle round the Sun) come to a same position after 60 years.^[24][25]

The following list presents the current 60-year cycle of the Tamil calendar:^[26]

There are twelve months in the Tamil calendar, with 29 to 32 days per month.^[27] Tamil months start and end based on the Sun's shift from onerasi to the other, and the names of the months are based on thenakshatra (star) that coincides with the start of thepournami (full moon) in that month.^[28] The Tamil calendar month starts a few days after the correspondingHindu calendar month as the Tamil calendar is asolar calendar, while the other is alunisolar calendar.^[29]

A Tamil year is divided into six seasons, each of which lasts two months.^[30][31]

The days of week (Kiḻamai) in the Tamil calendar relate to the celestial bodies in theSolar System:Sun,Moon,Mars,Mercury,Jupiter,Venus, andSaturn, in that order. A week usually starts with Sunday, and ends in a Saturday.^[32][33]

The various days and months of the Tamil Calendar are of specific significance toTamil Hindus. TheVakiya Panchangam is employed for calculation of sacred days, while theTirugaṇita Panchangam is employed forastrological calculations.^[34]

The months and their significant events and festivals are listed below.^[29][35]

• Chandravakyas
• Malayalam calendar
• Pambu Panchangam

• Tamil Calendar with Daily Panchangam
• Tamil Calendar for each year

• Hindu calendar
• Solar calendars
• Tamil culture
• Time in India

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