Why Hindu Festival Dates Change by City: Karva Chauth 2026

Karva Chauth 2026 is on Wednesday, October 28 in New York and on Thursday, October 29 in New Delhi. Both dates are correct. Karva Chauth is a day-long fast that ends when the moon rises. It is kept on the evening when Chaturthi, the 4th lunar day after the full moon, is running at moonrise.

Chaturthi begins at a single moment that every city shares: 7:37 PM on October 28 in UTC, the world's standard clock. In New York, that is 3:37 PM. The moon rises there at 7:31 PM, while Chaturthi is running. So New York keeps October 28.

In New Delhi, Chaturthi begins at 1:07 AM on October 29. The moon rises at 7:13 PM the evening before, too early to count. It rises again at 8:13 PM on October 29, with Chaturthi still running. So New Delhi keeps October 29.

It is one lunar day, checked against two different moonrises. We ran this rule for 9 cities with our API on October 11, 2026. Six keep Karva Chauth on October 28 and three on October 29. London's date needs a fallback rule, explained below. Picture an app that shows India's date to every user. By this rule, it gives a family in New York a date that is one day late.

Karva Chauth 2026 dates in 9 cities

We asked our festival endpoint for each city, using its latitude, longitude and time zone. All times are local. The festival is also spelled Karwa Chauth.

In our table, the split falls between London and Dubai. In the Americas, Chaturthi begins hours before the moon rises on October 28. In Dubai, New Delhi and Sydney, it begins after that evening's moon is already up. Their first moonrise inside Chaturthi comes a day later.

Dubai is the closest call. Its moon rises at 8:25 PM on October 29, just 16 minutes before Chaturthi ends.

A lunar day starts at the same moment everywhere

The Hindu calendar counts days by the Moon. A tithi, or lunar day, ends each time the Moon gains another 12 degrees on the Sun. Our public rulebook states this as rule PA-01.

A tithi does not follow the clock. This year's Karva Chauth Chaturthi lasts 21 hours and 3 minutes. It runs from 7:37 PM UTC on October 28 to 4:40 PM UTC on October 29. Every city shares that window. It ends at 12:40 PM on a New York clock and at 10:10 PM on a New Delhi clock.

A Hindu day runs from one sunrise to the next, as rule PA-04 says. A festival also needs its tithi running at a set part of that day, which our API calls the kaal. For Karva Chauth, the kaal is moonrise.

Why moonrise decides Karva Chauth

The fast ends when the moon comes up, so the test is one question. On which evening is Chaturthi running at moonrise?

In New York, only October 28 passes. The moon rises at 7:31 PM, 3 hours 54 minutes after Chaturthi begins. The next moonrise, at 8:33 PM on October 29, comes after Chaturthi has ended. In New Delhi, the October 28 moonrise comes almost 6 hours too early. The October 29 moonrise beats the end of Chaturthi by about 2 hours.

Here is a trap for app builders. Open the panchang, the Hindu calendar for one day, for New York on October 29. The tithi at sunrise is Chaturthi. An app that matches festivals to the sunrise tithi would print October 29 for New York. Yet by moonrise that evening, Chaturthi has been over for 7 hours 53 minutes.

Both dates appear online. On October 11, 2026, we read two web guides for New York. One gave October 28. The other gave October 29, with an 8:31 PM moonrise. That evening fails the moonrise test, since Chaturthi ends at 12:40 PM.

London: when neither moonrise counts

London is the hard case. Its moon rises at 5:28 PM on October 28, about 2 hours before Chaturthi starts. On October 29, it rises at 6:25 PM, 1 hour 45 minutes after Chaturthi ends. Chaturthi is running at neither moonrise.

When the main rule finds no day, a fallback rule must pick one. Our API picks the Hindu day that holds more of the tithi. London's sunrises come at 6:46 AM on October 28 and 6:48 AM on October 29. So the day that starts on October 28 holds 11 hours 11 minutes of Chaturthi. The next day holds 9 hours 52 minutes. So the API returns October 28. Its decided_by field gives the reason: "the tithi holds moonrise on no day; kept on the civil day it mostly falls in."

Not every calendar uses that fallback. A diaspora guide we read on October 11, 2026 gives October 29 for the UK.

Each festival has its own deciding time

Karva Chauth is the only festival in our API decided by moonrise. Of the 21 festivals the API ties to a tithi, sunrise decides 6, the afternoon 4 and the early evening 3.

Dussehra 2026 shows the afternoon rule. It needs Dashami, the 10th lunar day after the new moon, during the afternoon window (aparahna). Dashami begins at 7:20 AM UTC on October 20. That is 3:20 AM in New York, so the afternoon of October 20 is covered. In Sydney it is 6:20 PM, after that afternoon is over, so Sydney keeps October 21.

Diwali shows a date that holds still. Its evening worship, Lakshmi Puja, needs Amavasya, the new moon day, during the early evening window (pradosh). In 2026, Amavasya runs from 5:58 AM UTC on November 8 to 7:02 AM UTC on November 9. That covers the evening of November 8 in all 9 cities.

So you cannot code one fixed shift for users abroad. Compared with New Delhi, Karva Chauth comes a day earlier in the Americas and London. Dussehra comes a day later, and only in Sydney. Diwali falls on the same day in all 9 cities.

What this means for your app

One printed list will be wrong for some of your users. A correct setup does three things.

Use the user's place. Send latitude, longitude and a time zone name such as America/New_York. A fixed UTC offset breaks around daylight saving time. New York is 4 hours behind UTC on Karva Chauth but 5 hours behind on Diwali.

Work out each festival for each place. Each festival has its own deciding time, so each one splits the map in a different spot. One overseas date cannot cover them all.

Show the deciding time and the rule. The fast ends at moonrise, so the moonrise time belongs next to the date. "Moonrise 7:31 PM" also explains why New York differs from Delhi. When a fallback picks the day, as in London, say so.

For a puja store, the local date sets when kits must arrive and when reminders go out. For a publisher, each city page shows its own date. In a diaspora app, Jane Doe in Chicago sees October 28 and a 7:23 PM moonrise. Her family in New Delhi sees October 29.

Accounts open on November 26, 2026. Leave your email on our sign-up page to hear the day you can start.

How the API works out a festival date

One call returns one festival for one year at one place.

Example: John Doe, who lives in New York (America/New_York), Karva Chauth 2026.

GET /v1/festivals/karva-chauth?year=2026&latitude=40.7128&longitude=-74.006&timezone=America/New_York

{
  "festival": {
    "name": "Karva Chauth",
    "date": "2026-10-28",
    "kaal": "moonrise",
    "kaal_at": "2026-10-28T19:31:26-04:00",
    "decided_by": "the only day the tithi holds moonrise",
    "tithi": {
      "starts": "2026-10-28T15:37:14-04:00",
      "ends": "2026-10-29T12:40:38-04:00"
    }
  }
}

The date is the answer. The kaal names the part of the day that decided it, and kaal_at gives that moonrise. The decided_by field states the rule in words, and tithi lets anyone check the result.

GET /v1/festivals returns all 23 festivals for a year and place, with the same fields. GET /v1/panchang/month puts them on a month calendar. The Hindu calendar API page lists each call, and the panchang API page covers the daily calendar.

We test these rules against Drik Panchang, a published Hindu calendar. Our tests pin 161 festival dates: New Delhi from 2023 to 2028, and Beijing in 2026. All 161 matched when we ran the tests on October 11, 2026.

See your own city's calendar. Our free panchang tool shows the tithi, sunrise and sunset for any place and date.

The lunar day belongs to the whole world at once. The moonrise, the afternoon and the evening belong to each city. A festival date needs both, so it has to be worked out where your user lives.