Today, Tamil people follow the Tamil Sidereal Calendar for celebrating festivals. The Tamil calendar differs from International Civil calendar (widely in use) with variable months and year lengths. This in uncomfortable to the people as they cannot predict the calendar date without seeing panchang.

The New Tamil Calendar proposes to use the tropical mean year length and fixed month lengths. The World Tamil Calendar follows the same leap year rule as the Gregorian calendar. So the mean tropical year maintains the span of 365.2425 days. The calendar dates are permanently synchronized with Gregorian calendar. The Indian National Calendar, Nanaksahi Calendar and Bengali calendar are already synchronized with the Gregorian calendar.

Year[edit | edit source]

The Tamil year system is not a numerical system. It follows a 60-year cycle. Thiruvalluvar Year is the official Tamil calendar system in Tamilnadu. Thiruvalluvar year starts in the Month of Thai, and Tamil New Year starts in the month of Chithirai. So the New World Tamil Calendar only changes the structure not the year.

Month[edit | edit source]

The current Tamil calendar system, Days of the months varies from 29 days into 32 days dynamically. We will fix the dates of the months either 30 or 31 days only. Normal year consists of 5 months of 31 days and 7 month of 30 days (5 Kuril , 7 Nedil, i.e. 5 ocean, 7 continent). A leap year consists of 6 months of 30 days and 6 months of 30 days. 

Initially 5 months from chithirai to Avani will be fixed by 31 days. Remaining months are fixed by 30 days. In leap years, an additional day (Leap Day) is added at the end of Thai Month to honor thiruvalluvar, Tamil cultural festivals. Month names are either solar or lunar.

Overview
SI No Month Names in Solar Month Names in Lunar Gregorian Date Total Days
1 Mesham Chithirai Apr 14 31
2 Rishabam Vaikaasi May 15 31
3 Mithunam Aani June 15 31
4 Kadagam Aadi July 16 31
5 Simmam Aavani Aug 16 31
6 Kanni Purattasi Sep 16 30
7 Thulam Aippasi Oct 16 30
8 Vrichigam Karthigai Nov 15 30
9 Thanusu Maargazhi Dec 15 30
10 Magaram Thai Jan 14 30/31*
11 Kumbam Maasi Feb 13/14* 30
12 Meenam Panguni Mar 15 30

* - Leap Year.

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