How the timings on this site are computed
Sunrise and sunset
Sunrise and sunset are computed for each city from its coordinates with Astronomy Engine (Don Cross, MIT licence), the same ephemeris the app ships and runs offline; city coordinates and time zones come from GeoNames (CC BY 4.0). They are the moments the Sun's upper edge meets the horizon, with standard atmospheric refraction. Times are shown in the city's own local time and truncated to the minute, as printed almanacs do.
and
Thirukanitha positions the Sun and Moon astronomically (sidereal, Lahiri ayanamsa) and uses the city's real sunrise. Vakya follows the traditional vakya reckoning used by Tamil Nadu temples and printed almanacs: the day for Rahu Kalam and the other eighths is taken as 6 am to 6 pm, and the Tamil month, and star follow the vakya tables. Where the two land on different days, every page on this site shows both. See the differences →
| Vakya (வாக்கியம்) | Thirukanitha (திருக்கணிதம்) | |
|---|---|---|
| Sun and Moon | Traditional vakya tables | Astronomical positions, sidereal (Lahiri ayanamsa) |
| Day for Rahu Kalam and the eighths | 6 am to 6 pm (printed almanac) | The city's real sunrise to sunset |
| Used by | Tamil Nadu temples, printed and wall almanacs | Astronomical almanacs; this site's default outside India |
| Shown on this site | Default in India | Default abroad; beside Vakya wherever the two differ |
Rahu Kalam, ,
The day from sunrise to sunset is cut into eight equal parts. Rahu Kalam is part 8, 2, 7, 5, 6, 4, 3 on Sunday through Saturday; Emagandam is part 5, 4, 3, 2, 1, 7, 6; Kuligai part 7, 6, 5, 4, 3, 2, 1. Kuligai is shown without judgement: some lineages hold it good for lasting work, others avoid it for ceremonies.
Nalla Neram, Gowri and Horai
Nalla Neram is drawn from the auspicious parts of the day, trimmed where they meet Rahu Kalam or Emagandam. Gowri panchangam divides day and night into eight parts each by the weekday table; Amirtham, Laabam, Dhanam, Sugam and Uthi are good. Horai are the 24 planetary hours from sunrise, starting with the weekday's planet.
Observances, muhurtham and thevasam
Pradosham, Ekadasi, Amavasai, Pournami and the monthly vrathams follow the thithi or star that governs each at its traditional time of day. Festivals follow each festival's own rule (Tamil month plus thithi or star). Muhurtham days combine the month, weekday, thithi and star rules, with the window. Thevasam uses the thithi holding during aparahna (the fourth fifth of the day) in the Tamil month of death.
Conventions this site follows
Timings vs calendar. Every timing (sunrise, Rahu Kalam, Emagandam, Kuligai, Nalla Neram, Gowri, Horai) is shown first as computed from the city's real sunrise; the printed-almanac (Vakya, 6 am day) time is shown beside it. Calendar facts (Tamil date, thithi, star, festivals) follow Vakya in India and Thirukanitha elsewhere, with the other method beside them.
Pradosham. The pradosha kaalam shown is sunset to 6 nazhigai (2 h 24 min) after sunset, on the day Thirayodasi holds at that time. Many temples hold the Nandi abhishekam just before sunset, about 4:30 – 6:00 pm; follow your temple.
Tamil month start. When the Sun enters the next sign before sunset, that day is day 1 of the new Tamil month; after sunset, the next day is. Almanacs that use a different cut-off (midnight, or a fixed time) can start the month a day earlier.
Masa Sivarathiri. Under Thirukanitha it is the night on which waning Chathurdasi holds at nishita (around midnight); under Vakya it is the day Chathurdasi holds at the printed Vakya almanac's reference moment. Almanacs that use another rule can list the day before. Where two days qualify for an observance, both are shown as one occurrence ("16 – 17").
Eclipses. All lunar eclipses are listed with their visibility from Chennai; solar eclipses are listed when visible from Chennai. Penumbral lunar eclipses are marked faint.
Why dates differ abroad
A Tamil festival or fast is fixed by the thithi or star in force at the local sunrise (or at the time of day its rule names), and Pongal and the Tamil months by the moment the Sun enters a sign. Those moments happen at the same instant everywhere, but they fall at different local hours. So a festival that begins on a given day in India can begin the previous evening, local time, in London, Toronto or New York, and land on the previous civil day there; in Sydney or Melbourne it can fall a day later. Pages for cities abroad are computed for that city's own sunrise and time zone (Thirukanitha), and show India's date (the Chennai printed almanac) beside it when the two differ.
Deepavali 2026 is Sunday, 8 November 2026 in India (Chennai printed almanac), but Saturday, 7 November 2026 in Canada, UK, USA; Singapore, Malaysia, Sri Lanka, UAE, Australia keep India's day.
Thai Pongal 2027 is Friday, 15 January 2027 in India (Chennai printed almanac), but Thursday, 14 January 2027 in Canada, UK, USA; Singapore, Malaysia, Sri Lanka, UAE, Australia keep India's day.
Every major festival by country, year by year: Tamil festival dates abroad. Monthly observances in each city, for example Pradosham in London or Amavasai in Toronto. Temples abroad sometimes keep India's date instead; follow your local temple.
Verification
The engine is checked day by day for 2016–2036 against an independent astronomical reference, and those comparison fixtures are part of the app's test suite; days are also spot-checked by hand against printed Tamil almanacs. Where a printed almanac differs by a minute or two, that is usually rounding or a different sunrise definition. If you find a day that looks wrong, please tell us with the city, date and the almanac you compared with.
Limits
The data covers 2016 to 2036. Timings are for the listed city; nearby towns differ by a few minutes. This site gives calendar facts and the tradition's general guidance, not personal predictions. For weddings, house-warmings and rites, confirm the final time with your family priest or astrologer.