Udaya Tithi vs Vyapini Tithi: Which Festival Uses Which

Udaya tithi is the tithi that is running when the Sun rises. A Hindu civil day runs from one sunrise to the next and takes that tithi’s name for all of its hours, even if a new tithi begins before noon. That is why a panchang can show Krishna Chaturdashi for a date on which Diwali is celebrated, and why someone asking “udaya tithi ke hisab se” can get a different day from the festival calendar. The site’s festival table dates 29 of its 44 lunar festivals by the sunrise tithi. Of the other fifteen, thirteen are tested at a different moment of the day, and for those the table requires the tithi to be vyapini, present at that moment: pradosh-vyapini, nishita-vyapini, madhyahna-vyapini, aparahna-vyapini or sayahna-vyapini. Holika Dahan and Holi have a rule of their own.

This page sets out where that rule comes from, which moment the site’s table tests for each festival, and, for every festival day from 2026 to 2028 tested at madhyahna, aparahna, sayahna or nishita, the tithi its sunrise carried. The skipped and doubled tithis that also move dates have their own page, kshaya and vriddhi tithi.

When Udaya Tithi Is Taken, and When It Is Not

A detailed English account of the rules is P. V. Kane’s History of Dharmasastra, volume V, part 1, which summarises the medieval digests such as the Nirnayasindhu and the Kalanirnaya. Kane cites a Shruti saying that the forenoon belongs to the gods, midday to men and the afternoon to the pitrs, together with a verse of Manu, and draws the working rule: a religious act prescribed for the gods by day is begun in the morning, on the tithi current then, even when another tithi takes over later in the day. A vrata meant for the evening or the night is kept on the tithi current in the evening or the night, even if that tithi was not the one at sunrise.

The principle under both halves is that the time of a rite is not a detail. In Kane’s words the prescribed time is a nimitta, the occasion on which the rite falls due, and the proper tithi for an act is “that tithi which covers up the time (such as morning), noon, whole day &c at which a religious act is prescribed to be done”. In Kane’s account, udaya tithi is that rule applied to the morning.

The same chapter gives the vocabulary, following the Dharmasindhu’s scheme. A tithi that begins exactly at one sunrise and ends at the next is purna, complete; every other tithi is sakhanda, broken. A sakhanda tithi is shuddha, pure, when it holds from sunrise to sunset (or, for some tithis such as that of Shivaratri, up to midnight), and viddha, pierced, when it is mixed with its neighbour. Panchangs and the digests use one more term, vyapini, pervading: a tithi is “pradosh-vyapini” when it pervades the pradosh window, “nishita-vyapini” when it pervades the middle of the night, and so on.

The Six Moments in the Site’s Festival Table

The festival dates on this site come from a generator that tests each festival’s tithi at a single instant of the civil day, at New Delhi, and keeps the first day on which that instant falls inside the tithi. Kane records divisions of the day into two, three, four, five, eight and fifteen parts, and cites a digest that treats the five-part division, pratah, sangava, madhyahna, aparahna and sayahna, as the principal one in the shastric rules. The table’s afternoon and evening tests are placed inside that division.

Holika Dahan has a rule of its own, the Purnima at pradosh with Bhadra excluded, and Holi follows it the next morning. The table tests one instant. A panchang that prints an aparahna or nishita window from start to end may require the whole of it or most of it. The two usually agree, and the section on days too close to settle gives the two where they nearly part.

Every Case, 2026 to 2028

These are the 27 festival days in the 2026, 2027 and 2028 tables that are tested at madhyahna, aparahna, sayahna or nishita. The fourth column is the tithi current at New Delhi’s sunrise that morning; where it is not the festival’s own tithi, the last column gives how long after sunrise the festival’s tithi began. On 17 of the 27 days the sunrise still belonged to the previous tithi.

The pradosh festivals are tabled on the pradosh kaal page. Across the three years 6 of their 12 days carry the previous tithi at sunrise, and all six are the Diwali-week trio of Dhanteras, Narak Chaturdashi and Lakshmi Puja in 2026 and 2028; in 2027 each of the three tithis is already running when the Sun rises. One of them is a case of its own: in 2028 the Trayodashi of Dhanteras begins after sunset on 15 October and ends before sunset the next day, so it touches no sunset at all, and the generator keeps it, by its stated convention, on the day it begins.

Three Cases Worked Through

Dussehra. Vijayadashami is tested at aparahna, and in all three years its listed day dawns on Shukla Navami. The Dashami begins 6 h 26 min after sunrise on Tuesday 20 October 2026, 2 h 44 min after it on Saturday 9 October 2027 and 1 h 57 min after it on Wednesday 27 September 2028, and each time it is running by the afternoon and is over before the next afternoon. By the udaya reading alone the festival would sit a day later every year; the afternoon test keeps it on the day whose afternoon the Dashami holds.

Janmashtami 2027. The table lists Tuesday 24 August 2027. That morning the sunrise tithi is Krishna Saptami; the Krishna Ashtami begins only in the evening, 14 h 31 min after sunrise, and is running at midnight. The next morning, 25 August, is the one whose sunrise carries the Ashtami, so a calendar dating the festival by udaya tithi would print that day. The nishita test gives the 24th. The site’s own Janmashtami 2027 page gives the detail.

Ram Navami 2027. Here the two readings agree. The Shukla Navami is already running at sunrise on Thursday 15 April 2027 and still has 60 minutes to run at the midpoint of the day, so the madhyahna test and the udaya reading land on the same date. When the tithi has begun before dawn and lasts past the tested moment, the two readings cannot disagree.

Two Days Too Close to Settle

Two rows in the table pass their test at New Delhi by under 30 minutes: Krishna Janmashtami 2026, whose Ashtami has 16 minutes left at the table’s nishita instant, and Ganesh Chaturthi 2027, whose Chaturthi has 7 minutes left at New Delhi’s midday. The madhyahna instant depends on sunrise and sunset, which move with the city: a city whose midday falls later than New Delhi’s, or a panchang that requires the whole madhyahna window rather than its centre, can reach the other answer for the Chaturthi. The table’s nishita instant is fixed just before the date ends, and the middle of the night at New Delhi, halfway from sunset to the next sunrise, comes after that Ashtami has ended; a panchang that tests the centre of the night can reach the other answer for Janmashtami. This page treats a margin under 30 minutes as too close to call from computed minutes, the same margin the site’s Ekadashi pages use, and leaves the choice to the calendar a household follows.

The Bright-Half and Dark-Half Verse

Kane quotes a verse that gives a simpler rule: in the bright fortnight prefer the tithi current at sunrise, and in the dark fortnight the tithi current at sunset. He gives it as one of the considerations for the combinations of tithis that the yugmavakya, the digests’ rule of paired tithis, does not cover, where no express text speaks. Set beside the site’s table, the verse fits most bright-half festivals and few dark-half ones. Of its 35 bright-half festivals, 25 are tested at sunrise, close to what the verse says. Of its nine dark-half festivals only three, Dhanteras, Narak Chaturdashi and Diwali, are tested at sunset; Maha Shivratri and Krishna Janmashtami take the middle of the night, and the other four, among them Karva Chauth and Sakat Chauth, take sunrise.

When No Sunrise Holds the Tithi

The udaya reading breaks down altogether for a kshaya tithi, one that begins after a sunrise and ends before the next. Among the sunrise-rule festivals, eight days in 2026–28 fall on such a tithi, and the generator keeps each on the day its tithi begins.

One row of the first table is the same case: the Shukla Chaturdashi of Narasimha Jayanti 2028 begins 30 min after sunrise on 7 May and is gone before the next sunrise, so no morning carries its name and the sayahna test alone decides the day.

For a single day’s tithi at sunrise, the daily panchang prints it for New Delhi, and the city panchang pages give each city’s own sunrise and sunset. The festival dates for the year are on the 2027 festival calendar, and the day’s fifteen muhurtas, from which the madhyahna and aparahna divisions are counted, are on the muhurta page. In Hindi: उदया तिथि और व्यापिनी तिथि: कौन सा पर्व किस नियम से.

In Brief

• Udaya tithi: the tithi current at sunrise, which names the whole civil day
• Vyapini tithi: the tithi present at the moment a rite is prescribed for, such as pradosh, nishita, madhyahna or aparahna
• The rule behind both: the proper tithi is the one covering the prescribed time (Kane, History of Dharmasastra V.1)
• In the site’s table: 29 of 44 festivals by sunrise, fifteen by another moment
• 2026–28: 17 of 27 madhyahna, aparahna, sayahna and nishita days dawn on the previous tithi, and 6 of 12 pradosh days do