Ganesh Chaturthi — and which day it actually falls on
The popular claimTwo calendars, two dates. Which one is right?
Every year, two calendars in the same house give two different dates for Ganesh Chaturthi, and nobody explains why.
The disagreement is not sloppiness. It is two different rules being applied to the same sky, and only one of them is the rule for this particular festival.
The problem, in one sentence
A tithi is not a day.
A tithi is the interval in which the Moon gains twelve degrees on the Sun, and that interval begins and ends at whatever clock time the arithmetic gives — 3 in the afternoon, 11 at night, twenty minutes past seven in the morning. It does not politely start at sunrise and finish at the next one.
So a tithi routinely touches two calendar days, and somebody has to decide which of those two days the observance belongs to. That decision is a rule, the rules differ between festivals, and the differences are old, written down and argued about in the texts.
The default rule, and why it is not this one
For most observances the test is sunrise: the tithi running at sunrise gives the day its name. It is the common case, it is what most day-to-day panchang reading assumes, and it is why a calendar can print one tithi against one date without further explanation.
Ganesh Chaturthi does not use it. The rule for this festival is madhyāhna-vyāpinī — the Chaturthi that pervades madhyāhna, the midday portion of the day. The reason given in the nibandha literature is straightforward: the observance itself is a midday one, so the tithi must be present when the observance happens.
Madhyāhna here is not "12 o'clock". The daylight from sunrise to sunset is divided into five equal parts, and madhyāhna is the third of them. It moves with the season and with your longitude, which is why it has to be computed rather than looked up.
2026, computed
These are our own figures for Delhi, from the same engine that answers the daily panchang. Bhādrapada Śukla Chaturthī:
- Chaturthi begins — 7:07 AM on Monday 14 September 2026
- Chaturthi ends — 7:44 AM on Tuesday 15 September 2026
Now apply each rule.
By the sunrise rule. On the 14th, sunrise is 6:06 AM and the tithi still running is Tritiya — Chaturthi has not started. On the 15th, sunrise is 6:07 AM and Chaturthi is running, with about ninety minutes left in it. The sunrise test therefore points at Tuesday the 15th.
By madhyāhna-vyāpinī. On the 14th, madhyāhna runs 11:02 AM to 1:30 PM, and Chaturthi — which began at 7:07 that morning and runs all night — covers the whole of it. On the 15th, madhyāhna runs 11:02 AM to 1:29 PM, and Chaturthi ended at 7:44 that morning; the tithi at midday is Panchami. The madhyāhna test points at Monday the 14th.
The rule for this festival is madhyāhna, so the answer for Delhi in 2026 is Monday 14 September.
That is a year in which the two rules genuinely part company. In many years they agree and nobody notices there was a question.
Why the times above are not the times for you
Every figure on this page is for Delhi. Sunrise, sunset and therefore madhyāhna shift with longitude and latitude; the tithi boundary is a single instant everywhere, but the clock reading of that instant is local.
In a year where the tithi ends close to midday, that difference is enough to move the festival by a day between two cities. It is not an error when it happens. It is the arithmetic doing what it should.
Our daily panchang computes both, for your own city, from the actual positions.
What this page does not say
It does not tell you that observing on the wrong day carries a consequence. The texts settle which day the observance belongs to; they are answering a question of order, not issuing a threat, and we are not going to add one they did not make.
Where families follow a household or regional custom that differs, that custom is not being corrected here. What this page gives is the rule, its source, and the computation — so that a choice is made knowing what it is.
Source — Dharmasindhu and Nirnayasindhu, the standard nibandha authorities on festival date determination, on madhyahna-vyapini chaturthi
Every claim on this site names its source, and every calculator shows its arithmetic.