Amanta vs Purnimanta: Why North and South India Name Months Differently

Hindu lunar months can be counted in two ways. In the amanta system (amā-anta, "ending at the new moon") a month runs from one new moon to the next. In the purnimanta system (pūrṇimā-anta, "ending at the full moon") it runs from one full moon to the next. Both use the same twelve names and the same days. The only difference is the name given to the waning fortnight (Krishna Paksha): purnimanta calls it by the next month's name. That is why a festival can be "Shravana Krishna Ashtami" in a Maharashtra panchang and "Bhadrapada Krishna Ashtami" in an Uttar Pradesh panchang, and still fall on the same day.

The picture in one table

Follow one lunar cycle and the fortnight after it.

Stretch of days	Amanta label	Purnimanta label
New moon → full moon (waxing)	Shravana, Shukla Paksha	Shravana, Shukla Paksha
Full moon → new moon (waning)	Shravana, Krishna Paksha	Bhadrapada, Krishna Paksha
New moon → full moon (waxing)	Bhadrapada, Shukla Paksha	Bhadrapada, Shukla Paksha

• Shukla Paksha (bright fortnight): both systems use the same month name.
• Krishna Paksha (dark fortnight): the purnimanta month name is one ahead of the amanta name.

S. K. Chatterjee's account of Indian calendars puts it the same way: a purnimanta month starts a fortnight earlier than the amanta month of the same name, and ends in the middle of it.

Converting between them

• Purnimanta → amanta: if the date is in Krishna Paksha, go one month back. Purnimanta "Bhadrapada Krishna Ashtami" is amanta "Shravana Krishna Ashtami".
• Amanta → purnimanta: if the date is in Krishna Paksha, go one month forward.
• Shukla Paksha: nothing changes.

Festival examples

These describe how each day is labelled, not when it falls in any particular year.

Observance	Amanta label	Purnimanta label
Krishna Janmashtami	Shravana Krishna Ashtami	Bhadrapada Krishna Ashtami
Karva Chauth	Ashvina Krishna Chaturthi	Kartika Krishna Chaturthi
Maha Shivaratri	Magha Krishna Chaturdashi	Phalguna Krishna Chaturdashi
Ganesh Chaturthi	Bhadrapada Shukla Chaturthi	Bhadrapada Shukla Chaturthi (same)
Rama Navami	Chaitra Shukla Navami	Chaitra Shukla Navami (same)

Notice that the Shukla Paksha examples agree. Encyclopaedia pages and festival lists often mix the two conventions without saying so. We found one reference list that files Janmashtami under Shravana (the amanta label) but Karva Chauth under Kartika (the purnimanta label) in the same table. If a month name looks "wrong", check the paksha first.

Does the festival date itself change?

Not because of the month label. The two systems are only two ways of naming the same days. A Krishna Ashtami is the same Krishna Ashtami whatever you call its month.

Festival dates can differ between regions for other reasons:

• local sunrise, which decides which tithi "owns" a day;
• the rule a tradition uses for that observance, such as a moonrise, midnight or midday requirement;
• the calculation school;
• regional customs that tie a festival to a solar month instead of a lunar one.

See Why Panchang timings change with your city. Always confirm a date in a Panchang for your own city.

Who uses which?

This is the broad picture. Practice varies within states, between communities and between purposes, so treat it as a guide.

• Amanta: Maharashtra, Gujarat, Karnataka, Andhra Pradesh and Telangana, and Goa.
• Purnimanta: most of the north, including Uttar Pradesh, Bihar, Madhya Pradesh, Rajasthan, Delhi, Haryana, Himachal Pradesh, Uttarakhand, Jharkhand, Chhattisgarh, and Jammu and Kashmir.
• Solar-calendar regions: Tamil Nadu, Kerala, West Bengal, Odisha, Assam and Tripura count civil months by the Sun; Chatterjee adds that Punjab and Haryana partly do too. For religious lunar dates they use a lunar reckoning alongside. Chatterjee says amanta reckoning is used in all states for fixing lunar festival dates. Mishra's survey lists Odisha and Punjab as using purnimanta for religious dates. That is one of several points where sources disagree.

The two scholarly surveys we used (1987 and 2010) broadly agree on this split but differ in detail for a few states. Both predate the creation of Telangana in 2014; we list it with Andhra Pradesh, as current summaries such as Wikipedia's Hindu calendar article do.

The New Year wrinkle

Where the lunar year starts in Chaitra, both systems begin it on Chaitra Shukla Pratipada, the day after the new moon that begins the bright half of Chaitra. (Not every region starts its year in Chaitra: most of Gujarat, for example, begins it the day after Diwali.) In purnimanta reckoning, though, the month of Chaitra has already begun two weeks earlier, at the preceding full moon. So the Krishna half of purnimanta Chaitra belongs to the old year and the Shukla half to the new one. Mishra's survey describes the purnimanta year as starting in the middle of the purnimanta month of Chaitra.

How an extra month fits in

When an intercalary month (adhik maas) occurs, amanta reckoning simply inserts a whole extra new-moon-to-new-moon month before the regular one. In purnimanta reckoning the extra month sits inside the regular month of the same name: first the regular month's Krishna half, then the adhika month, then the regular month's Shukla half. Wikipedia's article on adhika masa gives this sequence. The physical days are identical in both systems; only the labelling differs. More in Adhik Maas and Kshaya Maas.

How to tell which system a panchang uses

• Look at the day after Purnima. If the month name changes there, the panchang is purnimanta. If it changes only after Amavasya, it is amanta.
• Look for labels. Some panchangs print both, marked "Amanta" and "Purnimanta".
• Look at Krishna Paksha festivals. If Janmashtami is filed under Bhadrapada, it is purnimanta.

Which one is "right"?

Neither. Both have long textual and regional backing; Mishra's survey notes that passages in the older Sanskrit literature (śruti and smṛti) can be quoted to justify either. Follow the system your family, temple or region uses, and simply keep the conversion rule in mind when reading a calendar from elsewhere.

For month names and their origins, see The Hindu lunar months. For the two fortnights, see Shukla Paksha and Krishna Paksha. To check today's paksha, open the daily Panchang; for the month name, use a panchang that says whether it is amanta or purnimanta.