How Festival Dates Are Actually Decided: Sunrise Tithi, Midday, Evening and Other Rules

Hindu festivals are tied to tithis, the lunar days. A tithi is the time the Moon takes to gain 12 degrees on the Sun, and that runs from about 19 to 26 hours, never exactly 24. It can start at any hour and end at any hour. A civil day, by contrast, runs from midnight to midnight, and a Panchang day from one sunrise to the next.

So a tithi routinely straddles two dates, begins in the afternoon and ends the next afternoon, or occasionally starts and ends between two sunrises. An almanac has to decide which date the festival belongs to, and it does so by a rule. Different rules are right for different festivals, and when two sources apply different rules, you get two dates for the same festival.

The simplest and most common rule is that a day takes the name of the tithi that is running at sunrise. This is called the udaya tithi rule. If Ashtami is on at sunrise, the day is Ashtami, even if it ends an hour later. Most festivals follow this rule: Ram Navami, Hanuman Jayanti, Akshaya Tritiya, Buddha Purnima, Raksha Bandhan, Krishna Janmashtami, Karva Chauth, Chhath Puja, Holika Dahan and Holi in this site's engine, along with the days of Shardiya Navratri.

Because sunrise depends on where you are, the udaya tithi can differ between cities. A tithi that ends at 6:10 AM is the sunrise tithi in a city where the Sun rises at 6:05 AM and is already over in one where it rises at 6:20 AM. That is the most common reason a festival date differs between Mumbai, Delhi and Kolkata, and it is why this site asks for your city.

Some observances are done at a particular time of day, and the day is chosen by what is running at that time. The Diwali cluster, Dhanteras, Lakshmi Puja, Govardhan Puja and Bhai Dooj, is dated by the tithi during Pradosh Kaal, the evening twilight after sunset, not at sunrise. In 2026, on the engine's Ahmedabad reference, Diwali's Amavasya runs from 11:28 AM on 8 November to 12:32 PM on 9 November. Because Amavasya is still running at the sunrise of 9 November, a plain sunrise rule would pick 9 November. Published almanacs agree on 8 November, the evening on which Amavasya is present after sunset.

Maha Shivaratri is a midnight observance, done in Nishita Kaal. Its civil day is conventionally the evening on which Chaturdashi is running, not the sunrise it touches. In 2026 the engine's Chaturdashi ran from 5:04 PM on 15 February to 5:34 PM on 16 February, so the festival is on 15 February. A plain sunrise rule would have given 16 February.

Ganesh Chaturthi is celebrated with a midday puja, and the classical rule is that the tithi at solar midday governs. In 2026 this gives 14 September, the day Chaturthi covers solar midday. A plain sunrise rule gives 15 September instead. Both dates follow a classical rule, and almanacs that publish 14 September are applying the midday one.

Vijayadashami is worshipped in the afternoon, so the engine uses an afternoon, or aparahna, anchor for it. Even so, published almanacs in some years disagree by up to two days for Vijayadashami and for the Durga Ashtami and Navami days around it, because the Ashwin Shukla Navami and Dashami tithis interact with special muhurtas, including the Vijaya Muhurta, that different almanacs weigh differently. Where this happens, the site states its rule and shows a note, and does not claim to settle it.

Sankashti Chaturthi is broken at moonrise, so the Chaturthi that counts is the one running at moonrise. That is why a Sankashti date can differ from a sunrise-based date, and why it varies more from city to city than most observances, since moonrise differs by city by many minutes and moves later each day.

Ekadashi and most of the monthly tithi vrats use the sunrise tithi. When the tithi is present at two sunrises, the site lists both days, since traditions differ on which to keep, and Vaishnava custom often prefers the second.

A few of the best-known days are not tithis. Makar Sankranti and Pongal follow the Sun's entry into Makara, a solar event, so they fall on nearly the same civil date every year. Puthandu and Vishu follow the Sun's entry into Mesha. Thaipusam and Onam are fixed by a nakshatra, Pushya in Thai and Shravana in Chingam, and the monthly Karthigai observance is the day the Moon is in Krittika. That is why these dates do not move in step with the lunar festivals.

Where a nakshatra begins during the day and runs into the next morning, there can be two dates, one for the nakshatra at sunset and one for the nakshatra at sunrise. For Karthigai the site lists both, marked at sunset and at sunrise, and explains which suits someone who lights a lamp at dusk and which suits someone who goes by the sunrise nakshatra.

Occasionally a tithi starts after one sunrise and ends before the next, so under the sunrise rule it does not exist for that month. This is a Kshaya tithi. In 2026, Chaitra Shukla Pratipada, the start of Chaitra Navratri and the day of Gudi Padwa and Ugadi, began at 6:52 AM on 19 March and ended at 4:52 AM on 20 March in the engine's Ahmedabad reference. That is after one sunrise and before the next. The widely published date is 19 March, the day the tithi begins.

The site handles this with a fallback. If a festival's sunrise scan finds no date in the year, it rescans using midday and flags the result as a Kshaya fallback. Before that fix the page would have returned nothing at all. A tithi that touches no sunrise is therefore listed on the day it begins.

About every third year the lunar calendar inserts an extra month, the Adhika Maas, which repeats the name of the next regular month. Festivals belong to the regular, or Nija, month, so a festival that falls in a month that has an Adhika twin has to be placed in the right one. The engine does this for observances such as Vat Purnima and Ganga Dussehra, which needed Adhika-aware selection and not a different anchor time.

North India names months from the day after the full moon (purnimanta), while Gujarat, Maharashtra and the south name them from the day after the new moon (amanta). For the bright fortnight both agree. For the dark fortnight the purnimanta month is one ahead. This changes the name of a month attached to a date, not the date itself, but it explains why one festival is described as falling in two different months. This site's festival engine names its months in the purnimanta style and its regional pages use the amanta style where that is the local convention.

Take a festival where the sunrise tithi is Dashami but the tithi the ritual needs, Ekadashi, begins mid-morning. One almanac applies the sunrise rule and keeps the next day. Another applies a rule that requires the tithi to cover a particular time and keeps this day. Both follow a classical rule and each can cite a text. Neither is an error.

On this site, a different date in the list from a printed almanac is therefore a question of which rule is applied, and in a minority of cases of which city's sunrise is used. The site lists the rule it applies for each festival on that festival's page and shows a note when sources are known to disagree. Dates on other websites are useful comparisons, but they are not the standard against which this one is judged.

Treat the date as a starting point and confirm it against the source that matters to you.

• Pick your city first, since the sunrise, moonrise and midday are all local.
• Check which rule the festival uses: sunrise, midday, evening, moonrise, solar or nakshatra.
• If the tithi is at two sunrises or none, expect two dates or a fallback.
• For a temple festival or family rite, follow the temple's or your priest's calendar.
• Compare against one printed local almanac, and ask why if they differ.