Calendar Converter for Near East Historians

This is a simple calendar conversion utility that displays a given date according to five primary standards: Gregorian, Julian, Hebrew, Islamic, and Persian (i.e., Solar Hijri). Change the date in any of the tables below, then click the corresponding “Calculate” button, and the equivalent date will appear in the other four calendars. There is now limited support for the Ottoman fiscal (or Rumi) calendar, a Julian derivative. In the Hebrew case, the year is also listed according to the Seleucid era. And for the benefit of historians of the later medieval and early modern Persianate world, this converter further indicates the animal year in which the given date falls. (See the “Notes & References” section below for discussion of such arcane points.)

The core of this project was adapted from the more extensive work of John Walker. I encourage you to spend some time exploring his calendar page and the underlying code, which he has graciously placed in the public domain.

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Gregorian Calendar

January February March April May June July August September October November December

Calculate Today

Julian Calendar

January February March April May June July August September October November December

Calculate

Hebrew Calendar

Calculate

Islamic Calendar

Muharram Safar Rabi‘ I Rabi‘ II Jumada I Jumada II Rajab Sha‘ban Ramadan Shawwal Dhu al-Qa‘dah Dhu al-Hijjah

Calculate

Persian (Sol. Hijri) Calendar

Farvardin Ordibehesht Khordad Tir Mordad Shahrivar Mehr Aban Azar Dey Bahman Esfand

Calculate

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Notes & References(show)

• Calendrical problems can be notoriously difficult for historians to resolve. After all, a calendar is no better than the way in which it has been observed by particular institutions, or the scrupulousness with which dates are recorded in the source materials available to us. With this in mind, a conversion program based on the formal rules of the included calendars is unlikely to answer all questions. The idea is to provide accurate calculations assuming ideal circumstances.
• If you find that a certain date appears to have been converted incorrectly on this page, please let me know by email. (This would come as a surprise. I’ve relied on the algorithms as coded by John Walker for years, with nary a problem.)
• In several of the Arab countries in which the Gregorian calendar is used for civil purposes, a different set of names is applied to the twelve months. Similarly, the Solar Hijri calendar is followed in Afghanistan, but with month names drawn from the Arabic zodiac signs, rather than from Middle Persian (as in the Iranian version shown above). And there is yet another naming convention in Pashto!
• The Ottoman fiscal calendar, also known as the Rumi calendar, represented a way for the Ottoman government to set dates for various administrative processes—e.g., collecting taxes and paying the army—that would remain in synchronization with the seasons. The value of this, as a complement to the lunar Islamic calendar, should be obvious. As early as 1740 CE, the Ottomans were using the Julian date of 1 March as the beginning of the fiscal year; and this system was developed further over time. There are a number of complications associated with this calendrical practice. The idea, at least initially, was for the numbering of years in the solar fiscal calendar to be kept in alignment with the Islamic calendar. This required dropping a year from the former every three decades. Eventually, as part of the Tanzimat reforms of 1839, it was decreed that the Julian calendar would be observed in a more systematic manner, in a variety of administrative contexts. From 1840 through early 1917 (when the policy was changed again), the Ottoman fiscal calendar followed relatively straightforward rules. The year began on 1 March, and the numbering reflected the Islamic, rather than the Christian era. The months had different names but otherwise tracked the Julian system. Converting from one to the other is simple. And so I have added support for this calendar, preliminarily, for the aforementioned period. The range may be expanded at some point. For a more detailed overview of the Ottoman fiscal calendar, see this article by Richard B. Rose.
• In the Hebrew calendar widget, the months are listed starting with Nisan, but each new year begins with Tishrei. This is simply a matter of convention. With regard to the Seleucid era, I have followed the method of subtracting 3,449 from anno mundi. That is, Seleucid year 1 opens with the month of Tishrei in 3450 AM, or September 312 BCE in the Julian calendar. If I have understood correctly, this was the prevalent way of reckoning the Seleucid era in Jewish contexts. See the Encyclopædia Iranica entry for a bit more background discussion.
• It should be noted that the Persian calendar included above is the version adopted in Iran in 1925, as a modernization of the Jalali calendar (which dated back to 1079 CE but had not been used consistently in the intervening eras). Why would this recent standard be helpful for history before the twentieth century? The key point is that communities in Greater Iran have, since ancient times, treated the March equinox as the beginning of a new year — i.e., the festival of Nowruz. This practice is formalized in the Solar Hijri calendar, with the first day of the year, 1 Farvardin, occurring at the March equinox as observed from central Iran (52.5 degrees east meridian). We can therefore use the modern calendar proleptically for calculations involving years in earlier periods of Iranian history. The practical significance of this will become clear in the following note…
• Most people are likely familiar with the Chinese zodiac system, in which each year is associated with an animal sign in a repeating twelve-year cycle. The traditional Chinese calendar is lunisolar, and the year begins with a new moon that may occur between 21 January and 20 February (Gregorian). Variants of this scheme have been followed, and in many cases continue to be used, in countries across Asia. During the Mongol period, the practice of classifying years with animals was brought to Iran, and, for a time, some authors of astronomical and historical works in Persian used the Chinese calendar directly as a way of dating events. The animal signs themselves became a lasting part of Persianate culture, except that there was (quite naturally) a shift toward setting the transition point between years at the March equinox. This convention took on importance in the historiography of the Timurid and Safavid periods — especially the latter. In several key Safavid Persian chronicles, insofar as an annalistic format is employed, each year-section begins at Nowruz and is labeled with the corresponding animal. (Months and days are given in the Islamic calendar only.) It is clear that authors of the time had some difficulty maintaining concordance between the solar and lunar schemes that they used; and this has occasionally led to confusion among modern historians. But that is a topic best left for another conversation. Returning to the matter of the Solar Hijri calendar, we have an accurate way of tracking the passage of solar years in Iran from one March equinox to the next, and so we need only a bit of modular arithmetic to calculate the animal sign associated with any date.
• For more on the use of the twelve-animal cycle in Persian, see this journal article by Charles Melville (of Cambridge University), and this one by Robert D. McChesney (of NYU).
• It may go without saying, but users of this program should exercise care when interpreting results, in proportion to the degree of precision that is required, and with particular sensitivity to breakpoints. If, for example, you were studying an event in Safavid history that took place within a few days of the March equinox, it could be difficult to determine which animal year was in effect, since the actual observance of Nowruz varied slightly based on a number of factors. But I hope you will find, as I have, that formally correct conversion of dates is more than adequate in almost all cases.

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© 2018 –22 T. S. Beers
The files relating to this page are available on GitHub under the MIT License.
I’m not much of a developer. If anything is messed up, please let me know by email!