Every year the same question comes up: one calendar says Janmashtami is on Monday, another says Tuesday. Both may be right — for different places, or by different rules. Here is why.
Each festival has its own rule
Most festivals are tied to a tithi, but not all of them look at the tithi at sunrise. Each has its own moment of the day:
- Ganesh Chaturthi and Ram Navami look at madhyahna, the middle of the day.
- Diwali (Lakshmi Puja) looks at pradosh, the evening after sunset, on Amavasya.
- Mahashivratri looks at nishita, the deep middle of the night, on Chaturdashi.
- Janmashtami looks at midnight on Ashtami, and many also consider the Rohini nakshatra.
- Ekadashi has its own rules about the tithi before it, and Smarta and Vaishnava traditions can keep it on different days.
A calendar that simply prints the tithi at sunrise will sometimes put a festival on the wrong day.
And the rule is applied at your place
Sunrise, noon, sunset and midnight all come at different clock times in different cities. Guwahati sees sunrise nearly an hour before Ahmedabad.
When a tithi begins or ends close to one of these moments, one city may have the tithi at its noon and another may not. The same festival, by the same rule, then falls on two different dates in two parts of India. Neither calendar is wrong.
Month names can differ too
In the north, the lunar month usually ends at the full Moon (purnimanta); in much of the west and south it ends at the new Moon (amanta). For the dark half of the month, the two systems give the same day different month names. The festival is the same day — only its month name differs.
Solar calendars
Odisha, Tamil Nadu, Kerala and Bengal also keep solar calendars, in which the month changes when the Sun enters a new sign (sankranti). Festivals such as Pana Sankranti, Puthandu, Vishu and Pohela Boishakh follow the Sun, not the Moon.
How to read a festival calendar
- Make sure it is worked out for your city, not for a single city for all of India.
- Check which rule it used — sunrise, noon, evening or midnight.
- If your family or temple follows a particular tradition, that tradition decides.
In short
- Each festival looks at a particular time of day, not always sunrise.
- That time comes at a different clock hour in each city, so dates can differ.
- A good calendar names the rule it used, for your place.