Purnimanta calendars end a lunar month on the full moon and amanta calendars end it on the new moon. The bright half of the month has the same name in both, but the dark half carries the next month's name in the North and the current one elsewhere. In 2026 that puts Kartik at 27 October to 24 November in purnimanta calendars and 10 November to 8 December in amanta ones.
You see it every festival season. A cousin in Lucknow says Kartik began this week, a friend in Pune says it has not started yet, and both of them are reading a perfectly good panchang. Neither is wrong. They are counting the month from different ends.
Purnimanta is a lunar month that runs from the day after one full moon to the next full moon, while amanta is a lunar month that runs from the day after one new moon to the next new moon. Both are old, both are still in daily use, and which one you follow mostly depends on where your family is from.
What is the difference between purnimanta and amanta?
The difference is where the month is cut. Purnimanta closes the month at the full moon (Purnima). Amanta closes it at the new moon (Amavasya). Either way a lunar month is one cycle of the Moon, about 29.5 days.
The Moon's cycle has two halves. The bright half, shukla paksha, runs from new moon to full moon. The dark half, krishna paksha, runs from full moon to new moon. Amanta keeps each month's two halves together in the order bright then dark. Purnimanta flips that, so a month there runs dark half first and bright half second.
Why do the two systems agree for two weeks and disagree for the rest?
They agree on the bright half and disagree on the dark half. Every shukla paksha has the same month name in both systems. Only the krishna paksha changes name, and in purnimanta it already belongs to the next month.
So the dates only line up from the new moon to the full moon. Take Ashwin in 2026. The full moon of Sharad Purnima, 25 October, is Ashwin Purnima in both systems, which is why the Sharad Purnima date raises no argument. The next day the dark half begins, and that is where the North and the rest part ways.
How does this play out for Kartik 2026?
Purnimanta Kartik runs from 27 October to 24 November 2026. Amanta Kartik runs from 10 November to 8 December 2026. Drik Panchang and several independent calendars agree on these windows.
The two weeks from 27 October to 9 November are the interesting stretch. A North Indian calendar calls that period the dark half of Kartik. A Maharashtra, Gujarat or Telugu calendar calls the very same days the dark half of Ashwin. Diwali on 8 November is a good example. It sits in Kartik for a North Indian family and in Ashwin for an amanta one, even though everybody lights lamps on the same evening.
From 10 November the two calendars say Kartik together, and they keep saying it until Kartik Purnima on 24 November. After that the North moves on to Margashirsha while the South and West still have a dark half of Kartik left to count until 8 December.
Who follows which system?
Purnimanta is the norm across North India, and amanta is the norm across most of South and West India. Maharashtra, Gujarat, Karnataka, Andhra Pradesh and Telangana count months amanta, as the Shravan listings do.
The split is a convention and not a law, and you will meet exceptions at the borders. Some regional calendars, panchang publishers and temples follow their own habit. If you have moved cities, your family's practice usually still decides, and a local pandit can settle it in one sentence. Our guide to Shravan 2026 shows the same split with real dates, 30 July in the North and 13 August elsewhere.
Does it change anything about your birth chart?
No. Your birth chart is built from the sidereal positions of the planets, your rising sign and your Moon sign, with tithi and nakshatra read off the Moon. None of that depends on whether your region names the month by the full moon or the new moon.
The month name matters for observance. It decides which fast, which vrat and which puja a given tithi belongs to, and it is why a festival can sit in a different month on a friend's calendar. If a chart reading and a calendar seem to disagree, work out first whether the question is about the sky or about the almanac. Our explainer on tithi versus date covers the other common source of mismatch, and Purnima versus Amavasya covers the two lunar turning points themselves.
Which calendar should you trust?
Trust the one your family and your local temple use. Neither system is more accurate than the other, since both track the same Moon. They only draw the monthly boundary in different places.
The practical habit is to ask which system a panchang or an app uses before you compare dates. Many apps default to purnimanta because of where their users are, and that is a design choice you can usually change in settings. When two sources give different month names for the same day, they probably use different systems and nobody has made an error.
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What is the difference between purnimanta and amanta?
Purnimanta calendars end each lunar month on the full moon, while amanta calendars end it on the new moon. The bright half of a month has the same name in both systems, but the dark half belongs to the next month in purnimanta and to the current month in amanta. That is why a date can fall in two different months depending on the calendar.
When does Kartik 2026 start?
In purnimanta calendars, used across North India, Kartik 2026 starts on 27 October and ends on Kartik Purnima, 24 November. In amanta calendars, used in much of South and West India, it starts on 10 November and ends on 8 December. Diwali on 8 November falls in Kartik in the first system and in Ashwin in the second.
Does purnimanta or amanta change my birth chart?
No. A Vedic birth chart uses sidereal planetary positions, your ascendant, your Moon sign and nakshatra, none of which depend on how a region names its lunar months. The choice only affects which month a festival or vrat is said to fall in, so it matters for observance dates and not for chart readings.