Regional Varieties of the Indian Calendars

Helmer Aslaksen and Akshay Regulagedda

Introduction

Probably the easiest way to classify Indian calendars is by their region of usage. It must be reiterated though, that such an exercise might be misleading. The classification is indeed not watertight; all calendars are intrinsically inter-linked with one another. With this caveat, we'll now traverse India on a calendrical vehicle of sorts. In particular, we try to ascertain the following elements in each region's calendrical practices:

Thanks to Akhil Doegar and Akshay Prasad for help with graphics.

Lunisolar calendars

The southern amanta calendar

The southern amanta lunisolar calendar is followed in the South and Southwest Indian states of Andhra Pradesh, Karnataka and Maharashtra. It is lunisolar; i.e., its days and months are calculated based on the motions of the Moon and the Sun. Like the Chinese calendar, the month is calculated from new Moon to new Moon. It differs from the Chinese calendar in that the day of the new Moon is considered the last day of the previous month instead of the first day of the new month.

In the Chinese calendar, the year is divided into 12 solar months by 12 principal solar terms or zhongqis. In the Indian calendar, the year is divided into 12 solar months or rasis by 12 principal solar terms or samkranti. In the Chinese calendar the starting point of both the lunar and the solar months are considered to be the whole days on which the new Moon and the zhongqis occur. However, in the Indian calendar, the new Moon and the samkranti are considered moments in time. This becomes important when computing leap months, since like in the Chinese calendar, a leap month (adhika masa) is added to the calendar on average every 2.7 years to offset the disparity in lengths between the lunar year and the sidereal year. In addition, a month (kshaya masa) is occasionally skipped.

The southern amanta calendar differs from the western amanta calendar in its treatment of kshaya masas, the New Year Day and the era followed. We believe that the southern amanta calendar follows the southern school for treating kshaya masas. Saha and Lahiri suggest that it follows the Salivahana Saka Era starting with Chaitra Sukla Pratipada [1], the lunar day after the last new Moon before the Mesha samkranti. The years are also named according to the names of the Jovian years (southern school [2]). The eras and handling of kshaya masas will be discussed in detail in their respective sections.

Western amanta calendar

As already mentioned, we believe it is important to distinguish between the amanta calendar practiced in South and West India. In West India, specifically, in the state of Gujarat, the amanta calendar is of two forms [3], one that starts with Aashaadha (followed in the Kathiawar region) and one that starts with Kartika (followed all throughout Gujarat). Both calendars follow the Vikrama Era and both also probably follow the northwestern school for kshaya months.

Purnimanta calendar

The Purnimanta calendar is followed in most of North India, i.e., in the states of Bihar, Himachal Pradesh, Uttar Pradesh, Haryana, Punjab, Jammu and Kashmir and Rajasthan [4]. (Earlier literature fails to mention Uttaranchal, Chattisgarh, Jharkhand and Delhi, but they are off-shots of bigger states and follow the same calendar). It differs from the amanta calendar in that the months are reckoned from full Moon to full Moon. Therefore, the Purnimanta calendar starts two weeks before the amanta calendar does; that is, it starts with the lunar day after the last full Moon before the Mesha samkranti. The Vikrama Era is followed [5], along with the northern school of Jovian year names [6].

Solar calendars

Malayali (Kerala) calendar

There are four regional variations of Indian solar calendars that differ in the way the start of the month is related to the samkranti. The samkranti is the moment when the Sun enters an Indian zodiac sign or rasi. The Malayali calendar is followed in the South Indian state of Kerala. It is a solar calendar so the months are defined according to the rasis The year starts with the Simha samkranti and follows the Kollam Era [7]. The month begins on the same day as the samkranti if it occurs before aparahna, i.e., three-fifths of a day. Otherwise, it begins on the next day.

Tamil calendar

The Tamil calendar is followed in Tamil Nadu. This calendar is also solar; the month begins on the same day as the samkranti if it occurs before sunset [8]. The Kali Era is followed along with the southern Jovian cycle. One peculiarity about the Tamil calendar is that its month names start with Chittirai [9] (Chaitra).

Bengali calendar

The Bengali calendar is followed in West Bengal, Assam and Tripura. The Era is the Bengali San. The rule for the beginning of the month is again different; the month begins on the day after the samkranti, if it occurs before midnight. Otherwise, it begins on the third day [10].

Oriya calendar

The Oriya calendar is followed in the eastern state of Orissa. In addition to the Bengali San, the Saka, Vilayati and Amli eras are followed [11]. The month begins on the same day as that of the samkranti [12].

Nanakshahi calendar

Promulgated in 1998 CE, the Nanakshahi calendar is followed by Sikhs in Punjab. It is linked to the Gregorian calendar, except in its usage of the Nanakshahi Era [13].

National calendar of 1957

Proposed by the Calendar Reform Committee of 1952 and promulgated in 1957 CE, the national calendar is a tropical calendar with fixed lengths of days and months. However, because it was totally different from the traditional calendars, it did not find much acceptance [14].

Skipped (kshaya) months

One of the most interesting aspects of the Indian lunisolar calendar is its kshaya masas, literally “decayed months”. Occasionally, certain months are skipped from the lunisolar calendar. We now try to understand the modalities behind this omission; we try to answer how, why, when and where it happens.

First, let's try to define a kshaya month. Chatterjee, in his work on Indian calendars, says that a certain lunar month “may completely overlap any of the short three nirayana solar months of Margasira, Pausha and Magha”, with the result that there will be no new Moon in the respective solar month. Consequently, there will be no lunar month named “after …this solar month” [27].

We learn the following from this statement: a) that the solar months of Margasira, Pausa and Magha are small, b) that at a certain time, there might be no new Moon in these months, and c) the corresponding lunar month is skipped from the calendar. Note that Chatterjee is silent on whether the skipped lunar month is amanta or purnimanta; a naive assumption would be that since he talks about new Moons, the month would be amanta. But, a study of the (Chaitradi) amanta and purnimanta calendars for the present year reveals that the difference between these two calendars is still two weeks. Therefore, it's safe to conclude that kshaya months were skipped from the purnimanta calendar as well.

Moreover, the statement about “corresponding lunar month” is unclear; are we talking about the lunar month with the same number as the new-Moon-lacking solar month? Or are we talking about the lunar month with the same name of the solar month? From looking at calendars, we see that it is the lunar month with the same name that gets skipped.

To account for a purnimanta kshaya, and to further clarify which month to skip, we re-phrase the definition of a kshaya month to be thus: In any given lunar year, if two consecutive samkrantis occur between two consecutive new Moons, then the lunar month, whether amanta or purnimanta, with the same name as the solar month in which this occurs, is skipped. As we shall see, such a re-phrasing is useful for computational purposes.

Treatment of kshaya months [35]

We may complete our discussion of kshaya months by describing the three Kshaya schools.

We may thus summarize Indian calendars in the following table.

State Calendar Era New Year Local Variation
Andhra Pradesh Southern amanta Salivahana Saka, Jovian cycle (southern school) One day after the last new Moon before the Mesha samkranti Probably southern school for kshaya
Assam Solar Kali, Bengali San Solar day after the Mesha samkranti Bengali rules for beginning of month
Bihar Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Chattisgarh Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Delhi Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Goa Southern amanta Salivahana Saka, Jovian cycle (southern school) One day after the last new Moon before the Mesha samkranti Probably southern school for kshaya
Gujarat Western amanta Vikrama Karthikaadi One day after Deepavali Probably northwestern school for kshaya
Gujarat - Kathiawar Western amanta Vikrama Aashaadhadi Ashaadha S 1 Probably northwestern school for kshaya
Haryana Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Himachal Pradesh Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Jammu and Kashmir Purnimanta Saptarishi, Laukika One day after the last full Moon before the Mesha samkranti  
Jharkhand Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Karnataka Southern amanta Salivahana Saka, Jovian cycle (southern school) One day after the last new Moon before the Mesha samkranti Probably southern school for kshaya
Kerala Solar Kollam Era Simha samkranti 1. Kerala rules for beginning of month.
2. Months named after rasis
Madhya Pradesh Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Maharashtra Southern amanta Salivahana Saka, Jovian cycle (southern school) One day after the last new Moon before the Mesha samkranti Probably southern school for kshaya
Orissa Solar Saka, Vilaayati, Aamli, Bengali San The Mesha samkranti  
Punjab Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Punjab – Nanakshahi Sidereal; fixed relative to Gregorian calendar Nanakshahi 14th March Uses the traditional names for Punjabi months
Rajasthan Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Tamil Nadu Solar Kali, Jovian cycle (southern school) The Mesha samkranti  
Tripura Solar Kali, Bengali San Solar day after the Mesha samkranti Bengali rules for beginning of month
Uttaranchal Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
Uttar Pradesh Purnimanta Vikrama Era (Chaitradi) One day after the last full Moon before the Mesha samkranti  
West Bengal Solar Kali, Bengali San Solar day after the Mesha samkranti Bengali rules for beginning of month

Note:

  1. The table is exhaustive neither in terms of calendars nor in terms of states. Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland and Sikkim were left out.
  2. Chatterjee mentions that the Orissa school for deciding the beginning of the solar month is also used in Punjab and Haryana “where the solar calendar is also used” [15].

Eras

The Indian calendar system follows a wide range of eras, some of historical interest. Also, we do not attempt to link individual calendars to eras, for the same calendar may be reckoned with two different eras in two different places [25].

Era Year zero Beginning of era with respect to individual year
Saka 78 CE Mesha samkranti, Chaitra S 1
Vikrama 57 CE Mesha samkranti, Chaitra S 1, Kartika S 1, Ashadha S 1
Kali 3101 BCE Mesha samkranti, Chaitra S 1
Kollam 824 CE Kanya samkranti, Simha samkranti
Bengali San 963 + solar years since 1556 CE Mesha samkranti

In addition, some regions also name their years according to the names of the Jovian years. Saha and Lahiri point out that there are two schools for this; the southern school names its years in continuous succession, while the northern school names its years corresponding to the present Jovian year [26].

Summary

Here is a picture that summarizes the different Indian calendars.

Questions

I have a lot of questions about this, and I would love to hear from you if you can help me add information. Here are some of the most pressing.

Links

New Years

Online calendars

State holidays

Web pages by the Society for the Confluence of Festivals in India

Deepavali in South Africa

References

  1. K.D. ABHAYANKAR, Our Debts to our Ancestors, in "Treasures of Ancient Indian Astronomy" (ed. K.D. Abhayankar and B.G. Sidharth), Ajanta Publications, Delhi. 1993.
  2. Helmer ASLAKSEN, The Mathematics of the Chinese Calendar, preprint, National University of Singapore, 1999.
  3. Apurba Kumar CHAKRAVARTY and S.K. CHATTERJEE, Indian Calendar from Post-Vedic Period to AD 1900, in "History of Astronomy in India" (ed. S.N. Sen and K.S. Shukla), Indian National Science Academy, New Delhi, 1985.
  4. S.K. CHATTERJEE, Indian Calendric System, Publications Division, Ministry of Information and Broadcasting, Government of India, 1988.
  5. Nachum DERSHOWITZ and Edward M. REINGOLD, Calendrical Calculations, Cambridge University Press, 2001.
  6. Nachum DERSHOWITZ and Edward M. REINGOLD, Indian Calendrical Calculations.
  7. Akshay REGULAGEDDA, Panchanga-Tantra: The Magic of the Indian Calendar System, Undergraduate Research Opportunities Programme in Science (UROPS) thesis, National University of Singapore, 2002.
  8. M.H. SAHA and N.C. LAHIRI, History of the Calendar in Different Countries Through the Ages (Part C of the Report of the Calendar Reform Committee), Council of Scientific and Industrial Research, New Delhi, 1992.
  9. Robert SEWELL and Sankara Balakrishna DIKSHIT, The Indian Calendar, Motilal Banarsidass Publishers Pte. Ltd., 1995.

Endnotes

Back to Helmer Aslaksen's page on Indian Calendars.


Helmer Aslaksen
Department of Mathematics
National University of Singapore
helmer.aslaksen@gmail.com

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