A day is not one thing. It is a sequence of windows, some open and some shut. This almanac computes the five limbs of the Hindu calendar, and the hours worth using, for any date and any city on earth.
Periods traditionally chosen for beginnings — worship, signing, departure, first steps.
| Muhurtham | Window |
|---|
Periods traditionally left alone. Nothing is started here; ongoing work continues.
| Period | Window |
|---|
Eight equal parts from sunrise to sunset. Amirdham, Subam and Labam are sought; Cara suits movement; Udvega, Kāla and Roga are avoided.
| Choghadiyā | From | To |
|---|
Eight equal parts from sunset to the next sunrise. The cycle continues five places on from the day's first.
| Choghadiyā | From | To |
|---|
Twelve planetary hours by day and twelve by night, running in the Chaldean order and opening with the lord of the weekday. Each hora lends its planet's nature to whatever is begun in it.
| Horai | From | To | Good for |
|---|
| Horai | From | To | Good for |
|---|
Pick the occasion, then narrow it to the exact work — or leave it on anything and every kind of work in that occasion is tested. Each day in the range is scored against the classical rules: the naṭchathiram the Moon sits in and which of the seven kinds it belongs to, the tithi's family, the weekday's lord, whether Bhathirai or Panchakam falls, whether Chāturmāsa or an adhika month bars the work, and whether one of the siddhi yogas forms. Dates are computed for your selected place.
A verdict on each occasion, the hours worth using, and the hour to leave alone — for the date and place set above. Save it, or send it to whoever is asking.
Each occasion takes the best score among the works it contains — so “a new purchase” reads Good if the day suits a vehicle even where it does not suit gold. Open the Find a date tab to see which work carried it.
The lunar day. The Moon pulls 12° ahead of the Sun and a thithi has passed. Because the Moon's speed varies, a thithi runs anywhere from about 20 to 27 hours, so it rarely lines up with a clock day. The thithi named for a day is the one in force at sunrise.
The weekday, and with it a ruling planet: Sooriyan, Chandran, Sevvai, Budhan, Guru, Sukkiran, Sani. The varam decides where Raagu Kaalam falls and sets the order of the horai.
Which of the 27 lunar mansions the Moon occupies. This is the single strongest factor in choosing a date — most rules for thirumanam, travel or gruhapravesam are naṭchathiram rules first.
The sum of the Sun's and Moon's longitudes, divided into 27 parts. Four of them — Vyatheepatham, Vaidhruthi, Vyagatham and Parigham — are treated as unfavourable.
Half a thithi. Eleven karanams cycle through the month; the seventh, Vishti, is Bhathirai, and beginnings are held back while it runs.
Divide sunrise-to-sunset into eight. One of those eighths, fixed by the weekday, belongs to Raagu. Nothing new is begun in it. Kuligai and Emagandam are two more of the eight.
The eighth of the day's fifteen muhurthams — roughly 24 minutes either side of true local noon. It is the all-purpose auspicious window and is said to overrule most minor blemishes. It is not used on Wednesdays.
The Tamil calendar is solar: the month turns when the Sun enters a new rāsi, so Chithirai begins at the Mesha sankranti in mid-April and the date counts from there. Thirumanam and gruhapravesam are not held in Aadi, Purattasi or Margazhi — a rule on the solar month, not on the lunar one.
The five days the Moon spends in Kumbam and Meenam rāsi, from Avittam to Revathi. Roofing, buying fuel, southward travel and cremation rites are deferred.
Eight parts of the day and eight of the night, each named for its temper. It is a Gujarati and Rajasthani reckoning rather than a Tamil one — the Tamil counterpart is Gowri Panchāngam, or Nalla Neram. See the note below on why that is not yet here.
Every rule in the date finder rests on this. The 27 mansions sort into seven temperaments, and a work is matched to the temperament that suits it — you plant a tree under a fixed star and buy a car under a moving one.
Nalla Neram, read off the Gowri Panchāngam, is what most Tamil families actually consult — not Choghadiyā. It divides the day and the night into eight parts each, named Amirdham, Uthi, Laabam, Dhanam and Sugam (good) and Rogam, Soram and Visham (avoided). It is not in this almanac yet, and the reason is worth stating plainly: it is not a formula. It is a table printed in the Pambu Panchāngam, and each weekday has its own sequence that no rule generates. Verified against published almanacs, Thursday runs Dhanam, Sugam, Soram, Uthi, Amirdham, Visham, Rogam, Laabam, while Saturday runs Soram, Uthi, Visham, Amirdham, Rogam, Laabam, Dhanam, Sugam — the same eight names in a different order, so the one cannot be derived from the other. Two of the seven rows are confirmed; the other five would have to be guessed, and a guessed Nalla Neram is worse than none. Until the full table is in hand, use Drik's Gowri Panchāngam, which is built from the Pambu Panchāngam directly.
Positions come from a full Meeus/ELP-2000 lunar series and the standard solar theory, corrected for nutation and ΔT, then converted to the sidereal zodiac with the Lahiri (Chitrapakṣa) ayanāṁśa — the same dṛk-gaṇitam basis used by mainstream panchāngams. Sunrise and sunset are true geometric rise and set of the upper limb with refraction (−0°50′), for your exact latitude and longitude, with your city's daylight-saving rules applied. Tested against published panchāngams, the tithi, naṭchathiram and yoga end times here land within about a minute.
If you want a second opinion, a regional variant, or a printed almanac for a whole year, these are the standard references:
The most thorough of them. Dṛk-gaṇitamm for 100,000+ cities, with a Tamil calendar, Gowri Nalla Neram and Karthigai days.
Daily panchāngam in Tamil and English for any place from 1900, with horai, Gowri Nalla Neram and a printable PDF.
The Gowri Panchāngam table for any day and city, taken from the Pambu Panchāngam. This is the one to open for Nalla Neram.
Strong on Gowri Panchāngam and horai, with muhūrtham pages organised by the task you have in mind.
Maintained for North American temples; many US and Canadian Tamil temple calendars are built from it.