Quick answer: the month boundary is different
Amanta and Purnimanta are two ways of placing the boundary of a Hindu lunar month. Amanta months end at Amavasya, the new moon; Purnimanta months end at Purnima, the full moon. The same lunar fortnight can therefore have a different month name in the two systems, even when both calendars refer to the same sky and civil date.
- Amanta: a month begins with Shukla Paksha after new moon.
- Purnimanta: a month begins with Krishna Paksha after full moon.
- Shukla Paksha month names usually match; Krishna Paksha labels can shift.
- Neither label alone proves that a Panchang date is wrong.
The practical fix is to compare the month convention before comparing a festival label. Write down the paksha, tithi, local date and the calendar tradition together. A line such as “Krishna Ashtami” without its month system can be incomplete when people in different regions are discussing the same observance.
What counts as a lunar month?
A lunar month follows the cycle of phases, not a fixed block of thirty civil dates. Amavasya is the new-moon boundary and Purnima is the full-moon boundary. The interval from one new moon to the next contains a waxing fortnight, Shukla Paksha, and a waning fortnight, Krishna Paksha. A calendar must decide where to put its month-name boundary within that cycle.
In the Amanta convention, the new moon closes the month. The next month starts as the Moon begins its waxing phase. In Purnimanta, the full moon closes the month; the next month starts with the waning phase. These descriptions concern how a calendar labels a lunation. They do not mean the Moon behaves differently in one region or that the tithi itself changes.
A tithi is calculated from the changing angular separation of the Sun and Moon. It can start or end at any clock time. A month name, paksha and tithi answer different questions: the month identifies a larger calendar cycle, paksha identifies the waxing or waning half, and tithi identifies a 12-degree interval. For the tithi/date distinction, see Tithi versus calendar date.
Why the Krishna Paksha name can shift
Consider the fortnight after a Chaitra full moon. Under Amanta, the month that began after the preceding new moon continues until the next new moon, so that waning fortnight is still called Chaitra Krishna. Under Purnimanta, a new month begins after the full moon, so the same fortnight can be called Vaishakha Krishna. At the following new moon, the waxing fortnight is labelled Vaishakha in both systems.
This is a naming offset of roughly one fortnight, not a disagreement about the phase or the day. A dated Panchang may show the same local sunrise, same tithi and same festival date while printing different month names. The reader should compare the underlying tithi and the observance rule before deciding that one entry is erroneous.
A worked reading: one Krishna Ashtami, two labels
| Calendar moment | Amanta label | Purnimanta label | What is shared |
|---|---|---|---|
| Waxing fortnight after the new moon | Chaitra Shukla | Chaitra Shukla | Same paksha name and month label |
| Waning fortnight after the full moon | Chaitra Krishna | Vaishakha Krishna | Same Moon phase and tithi sequence |
| A date printed by a local calendar | Local civil date | Local civil date | The date may be identical |
The table is a month-label illustration based on the standard correspondence between the systems; it is not a prediction for a particular year. In a real observance, the Gregorian date and tithi start/end come from the year and location. The month-system label helps explain the name, while a festival’s rule determines which day is observed.
If a family calendar says Chaitra Krishna and another says Vaishakha Krishna, ask which month boundary each uses. Then compare the tithi interval and local sunrise or other ritual checkpoint. Do not move the event by fifteen days just because the month name differs; the two labels can describe the same fortnight.
Where each convention is commonly encountered
Amanta calendars are widely used in parts of western and southern India, including communities in Maharashtra, Gujarat, Karnataka and Andhra Pradesh. Purnimanta calendars are common in several northern and central Indian traditions, including parts of Uttar Pradesh, Bihar and Rajasthan. These are broad patterns, not a rule for every household, temple, publisher or diaspora community.
Some regional calendars are solar rather than Amanta or Purnimanta lunisolar calendars. Tamil, Malayalam, Bengali and other regional systems have their own month structures and observance conventions. India does not use one single calendar format for every cultural and ritual purpose. A language spoken in a region is not enough to identify the month system a family follows.
For a puja or fast, use the Panchang followed by the temple or family that will observe it. For an academic comparison, name the system explicitly. For a shared article or message, include both month labels if the audience is mixed. This small detail prevents an ordinary calendar difference from turning into a dispute over who has the “right” date.
What changes—and what does not
| Item | Can the name differ? | How to compare it |
|---|---|---|
| Month label during Krishna Paksha | Yes | Ask whether the calendar is Amanta or Purnimanta |
| Tithi sequence | No, the same lunar phase sequence is being described | Compare tithi start/end and local date |
| Civil date | It can differ for other reasons | Check location, timezone and the observance rule |
| Festival observance | Regional rules may differ | Use the local temple or family convention |
| Solar calendar month | It follows a different calendar structure | Do not force it into a lunar-month label |
An Amanta/Purnimanta difference does not by itself explain every festival-date disagreement. Location, local sunrise, the tithi at the relevant ritual moment, leap-month naming and regional practice can also matter. If the dates still differ after you align the month system, compare those fields one at a time.
A five-step checklist for comparing two Panchangs
- Record the city and local timezone printed by each calendar.
- Identify whether each calendar uses Amanta, Purnimanta or a solar month system.
- Compare the paksha and tithi, including the start and end times.
- Find the festival’s stated checkpoint: sunrise, sunset, moonrise or another interval.
- For a ritual, follow the calendar of the family or temple conducting it; note regional exceptions.
A clear note could read: “Vaishakha Krishna Ashtami in the Purnimanta calendar; the corresponding Amanta label is Chaitra Krishna Ashtami; local observance follows the temple Panchang for Jaipur.” It gives readers enough context to understand a different month name without treating it as a different lunar event.
Frequently asked questions
These short answers explain the month boundary without replacing a local observance rule.
What is the main difference between Amanta and Purnimanta?
Amanta months end at the new moon; Purnimanta months end at the full moon. This can shift the month name attached to Krishna Paksha.
Are Amanta and Purnimanta dates different?
The month labels can differ even when the tithi and civil observance date are the same. Other local rules can also affect a date.
Which calendar should I follow for a fast?
Follow the Panchang used by the temple, family or community observing that fast. Do not choose by region alone.
Does Amanta mean the month starts at midnight?
No. It refers to the new-moon boundary of a lunar month, not the civil clock changing at midnight.
Do solar calendars use Amanta or Purnimanta?
No. A solar calendar organizes months by solar motion and has a different month structure.
Why do two websites name the same Krishna Paksha differently?
They may use different lunar-month boundaries. Check the month convention before treating the labels as a date error.