Ask two Hindu families in different parts of India which month Diwali falls in, and you may get two honest answers. One says Ashwina and the other says Kartika. Neither is wrong. They count months from different starting points, and the difference is called amanta and purnimanta. Once you see the rule, a great deal of the confusion about festival months goes away.
The two rules
Every lunar month has a bright half (Shukla paksha), from the new moon to the full moon, and a dark half (Krishna paksha), from the full moon to the next new moon. The only question is where a month begins and ends.
In the amanta system the month runs from new moon to new moon. The word comes from amanta, meaning ending at the amavasya, the new moon. The month opens with its bright half and closes with its dark half. In the purnimanta system the month runs from full moon to full moon, ending at the purnima. The month opens with its dark half and closes with its bright half.
The bright half sits in the same place in both systems, between a new moon and the next full moon, so its name never changes. Only the dark half is moved. In purnimanta the dark half belongs to the month that is about to be completed by the next full moon, so a purnimanta calendar names it for the month that follows in the amanta count.
Who uses which
The amanta system is the standard in Maharashtra, Goa, Karnataka, Andhra Pradesh, Telangana and Gujarat. The purnimanta system is standard in most of the north, including Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, Jharkhand, Haryana, Punjab, Himachal Pradesh, Uttarakhand and Delhi. A printed panchang says which count it follows, and some give both names. A diaspora family usually follows the system of the region its family came from. The solar calendars of Tamil Nadu, Kerala and Bengal are separate, and they are described on the hub page.
One fortnight, two labels
Take the fortnight that follows the full moon in the middle of an amanta month. For a family in Pune it is the dark half of that month. For a family in Lucknow it is the first half of the next month, because their month began at that full moon. The days are the same days with the same tithis, and only the month label differs.
A worked example from the computed months. The amanta month of Ashwina in 2026 runs from 10 October 2026, 09:20 PM, to 09 November 2026, 12:32 PM. Its bright half holds the nine nights of Sharad Navratri and Dussehra, and both systems agree that these belong to Ashwina. After the full moon in the middle, the dark half runs to the new moon of 09 November 2026. A southern or western calendar calls that dark half Ashwina Krishna paksha. A northern calendar calls it Kartika Krishna paksha. Karva Chauth, Dhanteras and Diwali fall in it.
Festivals with two labels
| Festival | Where it falls in the dark half | Amanta label | Purnimanta label |
|---|---|---|---|
| Diwali | The new moon, Amavasya | Ashwina | Kartika |
| Karva Chauth | Chaturthi, fourth day | Ashwina | Kartika |
| Dhanteras | Trayodashi, thirteenth day | Ashwina | Kartika |
| Janmashtami | Ashtami, eighth day | Shravana | Bhadrapada |
| Maha Shivaratri | Chaturdashi, fourteenth day | Magha | Phalguna |
| Pitru Paksha | The whole dark half | Bhadrapada | Ashwina |
Festivals of the bright half do not appear in the table, because they never change. Ganesh Chaturthi is Bhadrapada Shukla Chaturthi everywhere, Ram Navami is Chaitra Shukla Navami everywhere and Holi is the full moon of Phalguna everywhere. The pages on the months therefore list the bright-half festivals under one name and note where the dark-half ones are labelled differently.
Why this matters for the year
The two systems start the year at different places in practice. The lunar year is counted from Chaitra Shukla Pratipada in both, because that is the first day of the bright half. In the amanta count the year therefore begins on the first day of the month. In the purnimanta count Chaitra has been running for about two weeks already when the new year is celebrated, which looks odd to a newcomer, and the people who follow it simply regard the year as turning in the middle of the month. The year and its era count are on the pages for Vikram Samvat and Shaka Samvat.
When a festival is fixed by a tithi in the dark half, the label is only a name for the same night. Dates on this site are computed from the new moon to the new moon, as the published method describes on the method page, and every festival page names both labels where they differ. If you are comparing with a printed panchang, look for the tithi and the day of the week and not for the month name.
Frequently asked questions
↳ Which system is correct, amanta or purnimanta?
Both are traditional, and each is correct for the region that uses it. They describe the same Moon and the same tithis, and only the month name of the dark half differs.
↳ Is Diwali in Ashwina or Kartika?
It is the new moon at the end of Ashwina in the amanta system and the new moon in Kartika in the purnimanta system. It is the same night, which is why you will see both months named.
↳ Does the bright half ever change its month name?
No. The bright half, from new moon to full moon, has the same month name in both systems, so festivals such as Ram Navami, Ganesh Chaturthi and Navratri are never affected.
↳ Why is Pitru Paksha in two different months?
It is the dark half after the full moon of Bhadrapada. A southern or western calendar calls it Bhadrapada Krishna paksha, and a northern one calls it Ashwina Krishna paksha, for the same fifteen days.
↳ Which one does this website use?
The month tables on this site use the amanta count, with the instants of the new moon, and each page notes the purnimanta label for the dark half. The festival dates themselves are fixed by tithi and do not depend on the label.