Set your location to view the Tamil calendar. Open Settings ☰ and tap Show Calendar — your browser will ask permission to share your location (needed to compute sunrise/sunset).
The Tamil calendar (தமிழ் நாட்காட்டி) is a sidereal solar calendar. Its twelve months — Chithirai, Vaikasi, Aani, Aadi, Aavani, Purattasi, Aippasi, Karthigai, Margazhi, Thai, Maasi and Panguni — each correspond to the sun's transit through one sidereal zodiac sign (raasi). The year begins with Chithirai, around 14 April, and years are named in a repeating 60-year cycle.
This calendar uses the standard Tamil sunset rule for the start of a month: a day belongs to the month of the sun's raasi at sunset. If the sun enters a new sign (sankranti) before sunset, that day is the 1st of the new month; if the ingress is after sunset, the next day is the 1st. Because sunrise/sunset depend on your location, the Tamil date, tithi, nakshatra (star) and festival timings are all computed for the latitude, longitude and timezone you provide.
Festival labels are derived from the Tamil month, date, tithi and nakshatra. This is a curated set of the major festivals and recurring observances (Pournami, Amavasai, Ekadasi, Pongal, Puthandu, Karthigai Deepam and more), not an exhaustive list.