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This article treats of the reckoning of days, months and years in the calendar used by adherents of the Zoroastrian faith. Zoroastrian religious festivals are discussed elsewhere, but have a fixed relationship to Nawruz, the New Year festival, whose timing is discussed below. Three distinct versions of the calendar are currently in use by different Zoroastrian communities.
In this article, except where explicitly noted to the contrary, Western-style dates prior to October 5, 1582 AD are reckoned according to the Julian calendar; subsequent dates are according to the Gregorian calendar, in which 15 October 1582 (Gregorian) was the day following 4 October 1582 (Julian).
Old Avestan calendar 
The forerunner of all modern Zoroastrian calendars is the system used to reckon dates in the Persian Empire. In 539 BC, Persia's rulers conquered Babylon, and soon afterwards - at least by the 4th century BC - adopted the Babylonian method of reckoning months: 12 months each containing 30 days. The Zoroastrian calendar follows the Babylonian in relating the seventh and other days of the month to Ahura Mazda.
This 'Avestan Calendar' of 360 days required regular correction to keep it synchronized with the solar year; this was achieved by intercalating a 13th month roughly once every six years.
Intercalations did not always follow a regular pattern, but during the reign of Artaxerxes II (circa 380 BC) astronomers utilized a 19 year cycle which required the edition of a month called Addaru II month in years 3, 6, 8, 11 14 and 19, and the month Ululu II in year 17 of the cycle. Older research suggests the first intercalation took place in 309 BC. Fuller information on the naming of months will be found below, but it should be noted that the first month of the year was called Frawardin, and the first day of Frawardin was the 'New Year's Day' or Nawruz (also reckoned Now-Ruz, Nowruz, No Roz, No-Rooz, Norouz, or Navroz), from which all other religious observances were reckoned - this day being, in theory, the day of the Northern vernal equinox, 21 March (Gregorian).
Following Alexander's conquest of Persia in 330 BC, the Seleucids (312-248 BC) instituted the Hellenic practice of counting years from the start of an 'era', as opposed to starting a new count at the beginning of the reign of each individual king. They therefore counted years of the era of Alexander (now referred to as the Seleucid era). This practice was not considered acceptable to the Zoroastrian priests, who consequently founded a new era, the era of Zoroaster - which incidentally led to the first serious attempt to establish a historical date for the prophet. The Parthians (150-224 CE), who succeeded the Seleucids, continued the Seleucid/Hellenic tradition.
Development of a 365-day Calendar 
Five significant stages seem to have occurred in the introduction of a stable 365-day calendar. Mary Boyce has observed that contemporary scholars are divided on whether this 365-day calendar was in fact preceded by a 360-day calendar of Zoroastrian observances.
First: A 365-day calendar was introduced during the reign of the Sasanian emperor Ardashir I (226-241 AD). The names of months and of days of the month that had been used in Achaemenian times remained unaltered; the five additional days were inserted after the twelfth month. These five days were named Gatha or Gah days, after the ancient Avesta hymns of the same name. In 226 AD, 1 Frawardin and the New Year celebration of Nawruz had drifted to 1 October. The older custom of counting regnal years from the monarch's coronation was reinstated.
Second: After 46 years (226-272 AD), with 1 Frawardin now on 19 September, another calendar reform was implemented by Ardashir's grandson Hormazd I (272-273 AD). It seems that during the first year after implentation of the Gatha days, the population had not universally adopted the new dates for religious festivals, resulting in "official" celebrations takings place five days later than popular celebrations. In later years the population had observed the Gatha days, but the original five-day discrepancy persisted. Hormazd's reform was to link the popular and official observance dates to form continual six-day feasts. Nawruz was an exception: the first and the sixth days of the month were celebrated as different occasions. Lesser Nawruz was observed on 1 Frawardin. 6 Frawardin, became Greater Nawruz, a day of special festivity. Around the 10th century CE, the Greater Nawruz was associated with the return of the legendary king, Jamsed; in contemporary practice it is kept as the symbolic observance of Zoroaster’s birthday, or Khordad Sal.
Third: A major reform of the religious calendar was implemented some time between 399 and 518 AD. The names of the days and months were unaltered, but Nawruz would now be celebrated on the first day of Adur, hitherto the ninth month of the calendar. Other religious festivals were shifted to maintain their relative position to Nawruz. Mary Boyce has argued that, as part of this reform, the six-day festivals were compressed to five days. The major feasts, or gahambars, of contemporary Zoroastrian practice, are still kept as five-day observances today.
Fourth: By the reign of Yazdegird III (632-651 AD), the religious celebrations were again somewhat adrift with respect to their proper seasons. Therefore in 632 AD, the new year due to be celebrated on June 21 was brought ahead by the device of omitting that year's Gatha days; Nawruz was therefore kept on June 16. Most Persian Zoroastrians accepted and used this new calendar. By the 9th century, the Zoroastrian theologian Zadspram had noted that the state of affairs was less than optimal, and estimated that at the time of Final Judgement the two systems would be out of sync by four years.
Fifth: In 1006 AD, the month Frawardin had returned to the correct position so that 1 Frawardin coincided with the Northern vernal equinox. The religious festivals were therefore returned to their traditional months, with Nawruz once again being celebrated on 1 Frawardin.
The Reckoning of Years 
16 June 632 AD is the start date for the current mainstream Zoroastrian reckoning of years. Yazdegird III was the last monarch of the Sasanian dynasty, and since the custom at that time was to count regnal years since the monarch ascended the throne, the reckoning of years was continued, in the absence of a Zoroastrian monarch, under Islamic rule. Zoroastrian dates are distinguished by the suffix Y.Z. for Yazdegirdi Era. The usage "AY" is also found.
The contemporary Zoroastrian community in Mumbai, and in isolated pockets of Asia Minor, uses an alternative reckoning of years which predates the Yazdegirdi Era, being based on a supposed date of the birth of Zoroaster on 3 March 389 BC. On this calendar, 27 July 2000 AD was the first day of Zoroastrian year 2390.
Yet another form of reckoning is the Zarathushtrian (Zoroastrian) Religious Era (Z.E.R./ZRE), adopted in 1990 AD by the Zarathushtrian Assembly of California. This is based on the putative association of the mission of Zoroaster with the dawn of the astrological Age of Aries, calculated for this purpose to have been the Northward vernal equinox of 1737 BC. Hence the year 3738 ZRE began in 2000 AD. The Zoroastrian community, both in Iran and in diaspora, have also been said to have accepted it, the former doing so in 1993 AD. A briefing paper from the Zoroastrian Trust Funds of Europe indicates that they recognise this usage to have been pragmatically adopted by Zoroastrians in Iran, while the diaspora continues to use the YZ system.
The Qadimi Calendar 
The cycle of days and months unaltered since 16 June 632 AD, and the cycle of religious observances unaltered since at least 1006 CE, form a stable calendar which is still in use today. Although Persia came under Arab, Islamic, rule in 651 AD, the civil reckoning of months and days was only disrupted for a short time and had returned to use for civil purposes within a century.
Alternative Names 
To distinguish this calendar from others which developed in due course, the name Qadimi became attached to it - a name which means 'old' or 'ancient' and will also be found with alternative spellings:
- Qadmi (by contraction)
- Kadimi (a Parsi variant spelling)
- Kadmi (by contraction)
Relationship with the Gregorian Calendar 
The Julian Day Number of Nowruz, the first day, of Year Y of the Yazdegirdi Era is therefore 1952063 + (Y-1) x 365.
22 July 2000 AD was Nowruz and the first day of 1370 Y.Z. (or 3738 ZRE) according to the Qadimi reckoning.
In the Julian year 1300 AD, 669 Y.Z. began on 1 January, and 670 Y.Z. on 31 December of the same year.
The Shahanshahi Calendar 
A 365-day calendar drifts ahead of the solar year at a rate of approximately one day every four years. A 9th-century Zoroastrian text, the Denkard, explicitly acknowledged several methods of compensating for this drift:
- a leap-day every fourth year;
- adding ten days every fortieth year;
- a leap-month of 30 days once every 120 years;
- 5 months once every 600 years;
- the discrepancy would be a whole year once every 1,440 years.
The Denkard then states:
- The time of six hours should be kept apart from (i.e. not to be added to) the last days of the year for many years, till (the hours) amount to (a definite period of time)... And it is the admonition of the good faith that the rectification (of the calendar) should not be made till a month is completed (i.e. till the additional six hours every year amount to a month at the end of a hundred and twenty. years). And more than a period of five months should not be allowed (to accumulate.) [Parentheses appear as in original.]
The Denkard - which was not Zoroastrian Scripture but a religious manual - therefore favoured the solution of a leap-month once every 120 years, with a fall-back of adding 5 months after 600 years if this were missed. This practice was not, however, adopted by Zoroastrians living in Islamic Persia.
Many Zoroastrians migrated from the Middle East to India during the 10th century, becoming known in India as Parsis. They had knowledge of the Denkard's proposal: at some point between 1125 and 1129, the Parsi-Zoroastrians of the Indian subcontinent inserted such an embolismic month, named Aspandarmad vahizak (the month of Aspandarmad but with the suffix vahizak). That month would also be the last month intercalated: subsequent generations of Parsis neglected to insert a thirteenth month.
Around 1720 AD, an Irani-Zoroastrian priest named Jamasp Peshotan Velati travelled from Iran to India. Upon his arrival, he discovered that there was a difference of a month between the Parsi calendar and his own calendar. Velati brought this discrepancy to the attention of the priests of Surat, but no consensus as to which calendar was correct was reached. Around 1740 AD, some influential priests argued that since their visitor had been from the ancient 'homeland', his version of the calendar must be correct, and their own must be wrong. On June 6, 1745 AD, a number of Parsis in and around Surat adopted the calendar which had continued in use of Iran, now to be identified as the Qadimi reckoning. Other Parsis continued to use the reckoning which had become traditional in India, and call their calendar Shahanshahi.
Alternative Names 
The name Shahanshahi means 'imperial' and will also be found with alternative spellings:
- "Shenshai" - probably a corruption of 'imperial'
- Rasimi - 'traditional'
- Sharshai - of uncertain meaning
The anonymous author of Ahura.TheLalis.com website comments:
- ... adherents of other variants of the Zoroastrian calendar denigrate the Shenshai or Shahenshahi as "royalist".
Relationship with the Gregorian Calendar 
21 August 2000 AD was Nawruz and the first day of 1370 Y.Z. (or 3738 ZRE) according to the Shahanshahi reckoning.
Because the one-off intercalation of 30 days happened sometime before the Nawruz of 1129 AD, we can be confident that in that Julian year, 498 YZ began on 12 February by the Qadimi reckoning, but 12 March by the recently-introduced Shahanshahi.
The Julian Day Number of Nawruz, the first day, of all subsequent Shahanshahi years Y of the Yazdegirdi Era is therefore 1952093 + (Y-1) x 365.
The Fasli calendar 
At the start of the 20th century, Khurshedji Cama, a Bombay Parsi, founded the "Zarthosti Fasili Sal Mandal", or Zoroastrian Seasonal-Year Society. in 1906, the society published its proposal for a Zoroastrian calendar which was synchronised with the seasons. This Fasli calendar, as it became known, was based on an older model, introduced in 1079 during the reign of the Seljuk Malik Shah and which had been well received in agrarian communities.
The Fasli proposal had two useful features: a leap-day once every four years, and harmony with the solar year. The leap-day, called Avardad-sal-Gah (or in Pahlavi: Ruzevahizak), would be inserted, when required, after the five existing Gatha days at the end of the year. New Year's Day would be kept on the Northward vernal equinox, and if the leap-day was applied correctly, would not drift away from the spring. The Fasli society also claimed that their calendar was an accurate religious calendar, as opposed to the other two calendars, which they asserted were only political.
The new calendar received little support from the Indian Zoroastrian community, since it was considered to contradict the injunctions expressed in the Denkard. In Iran, however, the Fasli calendar gained momentum following a campaign in 1930 to persuade the Iranian Zoroastrians to adopt it, under the title of the Bastani (traditional) calendar. In 1925 AD, the Iranian Parliament had introduced a new Iranian calendar, which (independent of the Fasli movement) incorporated both points proposed by the Fasili Society, and since the Iranian national calendar had also retained the Zoroastrian names of the months, it was not a big step to integrate the two. The Bastani calendar was duly accepted by many of the Zoroastrians. Many orthodox Iranian Zoroastrians, especially the Sharifabadis of Yazd, continued to use the Qadimi, however.
Festivals in Leap Years 
The Zoroastrian Year, in Qadimi and Shahanshahi observance, concludes wiith ten days in memory of departed souls: five Mukhtad days on the last 5 days of the 12th month, and five more Mukhtad days, which are also the five-day festival of Hamaspathmaidyem, on the five Gatha days. The penultimate day of the twelfth month is Mareshpand Jashan.
In a common year (non-leap year) of the Fasli observance, Mukhtad is observed 11–20 March, with Hamaspathmaidyem and the Gatha days 16–20 March. Mareshpand Jashan is on 14 March.
In a leap year of the Fasli observance, Mukhtad is observed 10–19 March, with Hamaspathmaidyem and the Gatha days 15–19 March. Mareshpand Jashan is on 13 March. The leap day, 20 March, called Avardad-sal-Gah, is considered a duplication of Wahishtoisht, the fifth Gatha day, but is not reckoned as Mukhtad or Hamaspathmaidyem.
Reckoning of Years 
In 1906 AD, Nawruz of 1276 Y.Z. fell on 15 August for followers of the Qadimi calendar, and 14 September for those observing Shahanshahi. There was therefore a six-month gap between the Fasli and Qadimi New Year observances, and a seven-month gap to the Shahanshahi.
The on-line calendar converters cited at the bottom of this page all give the current Fasli year (following Nawruz in 2011 AD) as 1381 Y.Z. - the same year as the Qadimi and Shahanshahi. However, the accumulated leap days not reckoned in the latter two calendars add up to a whole year in just over 1508 years. Since there is exactly one Fasli year for every Gregorian year, then day one of the proleptic Fasli calendar would be 21 March (Gregorian) 631 AD, with Year 2 beginning on 21 March 632 AD. But Yazdegird III did not ascend the throne until 19 June 632 AD (Gregorian), leading to the curious quirk that the base date for the reckoning of years ends up in Year 2 of the Fasli calendar.
Alternative Names 
The name Fasli will also be found in alternative forms:
- "Bastani" - Iranian for 'traditional'
Relationship with the Gregorian Calendar 
21 March 2000 AD was Nawruz and the first day of 1370 Y.Z. (or 3738 ZRE) according to the Fasli reckoning.
Dr Ali Jafarey describes the Fasli calendar as
- ...an almost tropical calendar. It is corrected by observing the leap year.
Webster's Online direction and various unreferenced sources state that the Fasli calendar follows the Gregorian, and it is shown strictly following the Gregorian calendar in the period 2009-2031 AD in the tables published by R. E. Kadva. The Gregorian calendar itself, however, will not keep 21 March as the date of the Northern vernal equinox forever - it has a deviation of one day every 5025 years.
Relationship with the Iranian Calendar 
The civil calendar in Iran since 31 March 1925 AD has been the Solar Hejri calendar. This is strictly tied to the actual Northward equinox, rather than a mathematical approximation to it. An Iranian day is reckoned to begin at midnight. Iranian time is 3.5 hours ahead of GMT. New Year's Day is defined to be the day, as reckoned by Iranian time, when the Northward equinox (the precise moment in time when northern and southern hemispheres of the earth pass through the point of the earth's orbit when they are equally illuminated by the sun) occurs on or before noon of that day, or during the 12 hours following the noon of the preceding day. This means that the pattern of leap years in the Iranian calendar is complex - usually following a 33-year cycle where the leap day is inserted every fourth year, but in year 33 instead of year 32, but with occasional 27 or 35 year cycles.
From 1960 to 1995, the Northward equinox always fell at such a time that New Year's Day in Iran occurred on the day called 21 March in the Western calendar. But this equivalence was not always true before March 1960, and the exact correspondence broke down again in 1996. In 1959, and at four-year intervals back to 1927, Iranian New Year's Day fell on 22 March in the Gregorian calendar. In 1996, and subsequent Gregorian leap years, Iranian New Year's Day falls on 20 March. The pattern will shift back to a matching set of leap years in 2096 AD.
The sources cited above state that the Fasli calendar both follows the Gregorian and was such that New Year's Day coincided with vernal equinox. These two statements are incompatible. The Fasli calendar cannot track both the Gregorian leap years and strictly start on the vernal equinox; further, any calendar strictly tied to the 'day of the equinox' must define when the day starts and ends, which depends on longitude.
A briefing paper from the Zoroastrian Trust Funds of Europe indicates that
- ...the Irani Zoroastrian calendar does not shift and commences on 21st March. But it is important to note that all Iranians including Zoroastrians celebrate NoRuz (Nawruz) on the actual day of the Northward equinox, therefore some years it can be 20th / 22nd March.
Astronomical and Mystical Aspects of the Calendars 
The three different Zoroastrian calendar-traditions are similar in regard of the principle of the beginning of the months. The Fasli, Qadimi and the Shahanshahi all (notionally) start each of the 30 day long months with the Sun entering a new constellation, similar to the Vedic (Hindu) Solar calendars as reflected in the Jyotisha (Vedic Astrology), and the Armenian calendar, but different from the Iranian (Jalaali) Calendar, the Julian Calendar, the Mayan Haab Calendar and the French Revolutionary Calendar, whose epochs of the months are fixed to the equinoxes/solstices, as are the signs of Western Astrology. The Qadimi and the Shhanshahi Zoroastrian Calendar use merely five epigomenal days, similar to the French Revolutionary, and the Coptic calendar, so their year count slowly travels through the astronomical year. Thus the Qadimi variant of the Zoroastrian calendar keeps track of precession, pointing towards an esoteric (hidden) calculus of world ages.
The Qadimi (traditional) Zoroastrian calendar puts the month of Dae (pronounced "Day") with the Sun entering the constellation of Taurus (specifically the Pleiades); thus apparently (theory) recalling the time of the origination of the zoroastrian calendar, and its relation to the discovery of the precession. At that time, one very well may conclude, that the vernal equinox also marked the sun's entrance into this constellation of the Golden Calf, the Taurus. According to Mary Boyce,
- It seems a reasonable surmise that Nawruz, the holiest of them all, with deep doctrinal significance, was founded by Zoroaster himself.
Future Developments of the Calendars 
The Fasli Calendar has become very popular outside India, especially in the West, but many Parsis believe that adding a leap day is against the rules, and they mostly continue to use the Shahanshahi Calendar. There is a proposal to correct matters by restoring the leap month, but unless this happens, the Shahanshahi and Qadimi years will continue to start earlier and earlier... the unrevised Qadimi Calendar would eventually coincide with the Fasli Calendar in Gregorian Year 2508, the Shahanshahi New Year will next fall on 21 March in 2632.
In 1992, all three calendars happened to have the first day of a month on the same day. Many Zoroastrians suggested a consolidation of the calendars: no consensus could be reached, though some took this opportunity to switch to the Fasli observance. Some priests objected on the grounds that if they were to switch, the religious implements they utilised would require re-consecration, at not insignificant expense.
It has also been proposed that the Shahanshahi calendar could be brought back into harmony through the intercalation of whole months.
In the UK, most Zoroastrians are Indians who follow the Shahanashai calendar. Nevertheless, noting that Iranian Zoroastrians mostly follow the Fasli calendar, the ZTFE (the official Zoroastrian charity and London centre of worship) marks observances of both calendars.
The Division of Time 
Divisions of the day 
A day is reckoned to begin at dawn, as attested by Chapter 25 of the 9th-century work, the Bundahishn; morning hours before dawn are assigned to the previous calendar day. Each day is divided into five watches:
- Hawan (sunrise to noon)
- Rapithwin or Second Hawan (noon to 3 p.m.)
- Uzerin (3 p.m. to sunset)
- Aiwisruthrem (sunset to midnight)
- Ushahin (midnight to sunrise)
In medieval times, according to the Bundahishn, in winter there were only four periods, with Hawan extending from daybreak until Uziran, with the omission of Rapithwan.
Naming of months and days 
The months and the days of the month in the Zoroastrian calendar are dedicated to, and named after, a divinity or divine concept. The religious importance of the calendar dedications is very significant. Not only does the calendar establish the hierarchy of the major divinities, it ensures the frequent invocation of their names since the divinities of both day and month are mentioned at every Zoroastrian act of worship.
Day names 
The tradition of naming the days and months after divinities was based on a similar Egyptian custom, and was instituted at some point between 458 and 330 BC, very probably during the reign of Artaxerxes II (404-358 BC). "The last evidence for the use ... with Old Persian month-names ... comes from 458BCE, ... after which the Elamite tablets cease. " No dated West-Iranian documents from between 458 BC and 330 BC survive, but the fact that the Zoroastrian calendar was created some time during that period can be inferred from its use In a number of far-flung lands which had formerly been parts of the Achaemenid Empire.
The oldest (though not dateable) testimony for the existence of the day dedications comes from Yasna 16, a section of the Yasna liturgy that is - for the most part - a veneration to the 30 divinities with day-name dedications. The Siroza - a two-part Avesta text with individual dedications to the 30 calendar divinities - has the same sequence.
|1.||Dadvah Ahura Mazdā, 2. Vohu Manah, 3. Aša Vahišta, 4. Khšathra Vairya, 5. Spenta Ārmaiti, 6. Haurvatāt, 7. Ameretāt|
|8.||Dadvah Ahura Mazdā, 9. Ātar, 10. Āpō, 11. Hvar, 12. Māh, 13. Tištrya, 14. Geuš Urvan|
|15.||Dadvah Ahura Mazdā, 16. Mithra, 17. Sraoša, 18. Rašnu, 19. Fravašayō, 20. Verethragna, 21. Rāman, 22. Vāta|
|23.||Dadvah Ahura Mazdā, 24. Daēna, 25. Aši, 26. Arštāt, 27. Asmān, 28. Zam, 29. Manthra Spenta, 30. Anaghra Raočā.|
The quaternary dedication to Ahura Mazda was perhaps a compromise between orthodox and heterodox factions, with the 8th, 15th and 23rd day of the calendar perhaps originally having been dedicated to Apam Napat, Haoma, and Dahmān Afrīn. The dedication to the Ahuric Apam Napat would almost certainly have been an issue for devotees of Aredvi Sura Anahita, whose shrine cult was enormously popular between the 4th century BC and the 3rd century AD and who is (accretions included) a functional equal of Apam Napat. To this day these three divinities are considered 'extra-calendary' divinites inasfar as they invoked together with the other 27, so making a list of 30 discrete entities.
The 2nd through 7th days are dedicated to the Amesha Spentas, the six 'divine sparks' through whom all subsequent creation was accomplished, and who - in present-day Zoroastrianism - are the archangels.
Days 9 through 13 are dedications to five yazatas of the litanies (Niyayeshes): Fire (Atar), Water (Apo), Sun (Hvar), Moon (Mah), the star Sirius (Tištrya) that here perhaps represents the firmament in its entirety. Day 14 is dedicated to the soul of the Ox (Geush Urvan), linked with and representing all animal creation.
Day 16, leading the second half of the days of the month, is dedicated to the divinity of oath, Mithra (like Apam Napat of the Ahuric triad). He is followed by those closest to him, Sraoša and Rašnu, likewise judges of the soul; the representatives of which, the Fravashi(s), come next. Verethragna, Rāman, Vāta are respectively the hypostases of victory, the breath of life, and the (other) divinity of the wind and 'space'.
The last group represent the more 'abstract' emanations: Religion (Daena), Recompense (Ashi), and Justice (Arshtat); Sky (Asman) and Earth (Zam); Sacred Invocation (Manthra Spenta) and Endless Light (Anaghra Raocha).
In present-day use, the day and month names are the Middle Persian equivalents of the divine names or the concepts, but in some cases reflect Semitic influences (for instance Tištrya appears as Tir, which Boyce (1982:31-33) asserts is derived from Nabu-*Tiri). The names of the 8th, 15th, and 23rd day of the month - reflecting Babylonian practice of dividing the month into four periods - can today be distinguished from one another: These three days are named Dae-pa Adar, Dae-pa Mehr, and Dae-pa Din, Middle Persian expressions meaning 'Creator of' (respectively) Atar, Mithra, and Daena.
What might loosely be called weeks are the divisions of days 1-7, 8-14, 15-22 and 23-30 of each month - two weeks of seven days followed by two weeks of eight. The Gatha days at the end of the year do not belong to any such week.
Month names 
Twelve divinities to whom days of the month are dedicated also have months dedicated to them. The month dedicated to Ahura Mazda is a special case - that month is named after Mazda's stock epithet, "Creator" (Avestan Dadvah, whence Zoroastrian Middle Persian Dae), rather than after His proper name.
Seven of the twelve-month names occur at various points in the surviving Avesta texts, but an enumeration similar to the ones for day names does not exist in scripture. Lists of month names are however known from commentaries on the Avesta texts, from various regional Zoroastrian calendars of the 3rd to 7th centuries, and from living usage. That these names have an Old Iranian origin and are not merely Middle Iranian innovations may be inferred from the fact that several regional variants reflect Old Iranian genitive singular forms, that is, they preserve an implicit "(month) of".
The month-names (with Avestan language names in parentheses), in the ordinal sequence used today, are:
The days on which day-name and month-name dedications intersect are festival days (name-day feast days) of special worship. Because Ahura Mazda has four day-name dedications, the month dedicated to Him has four intersections (the first, eighth, fifteenth and twenty-third day of the tenth month). The others have one intersection each, for example, the nineteenth day of the first month is the day of special worship of the Fravashis.
There is some evidence that suggests that in ancient practice Dae was the first month of the year, and Frawardin the last. In a 9th-century text, Zoroaster's age at the time of his death is stated to have been 77 years and 40 days (Zadspram 23.9), but the "40 days" do not correspond to the difference between the traditional "death day" (11th of Dae) and "birthday" (6th of Frawardin) unless Dae had once been the first month of the year and Frawardin the last. The festival of Frawardigan is held on the last days of the year, instead of following the name-day feast of the Fravashis (nineteenth day of the month of Frawardin, and also called Frawardigan)..
See also 
Calendar tables 
- Table mapping Fasli calendar to a Gregorian non-leap year. During a leap year, the mapping for the last 21 days of the Fasli year must be adjusted by subtracting 1 from the March date.
- Table for 1375 YZ. This table shows how the year 1375 YZ corresponds to Gregorian dates using the three Zoroastrian calendars, with links back to 1374, 1373 and 1372 YZ.
- Perpetual Fasli Calendar
- Zoroastrian Calendar of months and days
Calendar calculators 
- Excel/VBA (Automated) Zoroastrian Shehenshahi Calendar from 1900-2100 Click here to download (Copyright - Cyrus Sidhva, Auckland,NZ)
- Conversion tool for Gregorian dates from 1006 AD to 2400 AD (good for all dates 374 YZ to 1770 YZ). It can adjust for the fact that events between midnight and 6 a.m. on a Gregorian date fall on the previous Zoroastrian Day. Shows month view, year view, moon phases and 'Chaugadiyas'.
- The facility above is also available in Gujararti.
- A conversion tool for all three variant calendars, good for AD dates 1911-2030, also with ability to display Zoroastrian dates on a month-to-view page of the Gregorian calendar for 1911-1930.
- Another implementation of the zanc.org calendar above.
- RozCalc - Zoroastrian Calendar Calculator
- Parsical - Zoroastrian Shahenshahi calendar application
- The list is based on Kotwal F.M. and Boyd, J. A Guide to the Zoroastrian Religion, Scholars Press, 1982.
- Boyce, Mary (ed. & trans.). Textual Sources for the Study of Zoroastrianism. University of Chicago Press, 1984, p. 19-20.
- al Biruni, ed. Sachau E.. Chronology of ancient nations, p. 11 of Arabic (1000 AD), p. 12 of Sachau translation (1879 AD), online at http://www.archive.org/stream/chronologyofanci00biru#page/12/mode/2up
- Boyce, Mary (on behalf of the Persian Heritage Foundation). Zoroastrianism - Its Antiquity and Constant Vigour. Mazda Publishers, 1992, p. 108.
- Bickerman, E. J.. Chronology of the Ancient World. Thames & Hudson, 1968, p. 24.
- The Zoroastrian religious calendar, http://www.avesta.org/zcal.html - accessed 15 October 2011
- Panaino, Antonio. Calendars, in Encyclopaedia Iranica, Vol. IV, Fasc. 6-7, pp. 658-677, online version at http://www.iranicaonline.org/articles/calendars - accessed 17 October 2011
- Drouin, M. E.. Revue Archéologique, 1889, ii 43 ff
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