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Egyptian Dates

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This page gives access to a set of conversion tables for determining the Julian equivalent of Egyptian civil and lunar dates in the Ptolemaic era. Two tables are provided: a table converting civil dates to Julian dates, and a table notionally converting lunar dates to civil dates according to the lunar cycle of pCarlsberg 9.

The Egyptian Civil Calendar                                                                                     The Egyptian Lunar Calendar

The Egyptian civil calendar has the simplest structure of any calendar that has ever been devised, except for the method of counting years.

The Day

The Egyptian day started at dawn, or perhaps sunrise. The exact starting point is a matter of controversy. The difference may have a significant impact on Egyptian chronology, since it affects the Egyptian date assigned to a heliacal rising of Sothis, and hence the conversion of that date to a Julian year. However, this controversy does not affect Egyptian chronology in the period under review.

By convention, an Egyptian / Julian conversion refers to the daylight hours. Since the Julian day starts at midnight, the time between midnight and dawn (or sunrise) for a given Julian day belongs to the previous Egyptian day; the same time, for a given Egyptian day, belongs to the next Julian day.

The Month

During the Ptolemaic era, as in pharaonic times, the Egyptian civil year was 365 days long. Starting in the reign of Augustus, an additional day was inserted every four years. The year consisted of 12 months of 30 days each and 5 (or 6) additional days at the end of the year. Days were numbered from 1 to 30 within a month.

Months were named in two different ways. For most of pharaonic history, the months were grouped into three sets of four months each. Each set was assigned to a season -- Akhet, Peret or Shomu. Hence the months were named I Akhet, II Akhet etc. This system continued to be used in the Ptolemaic period, particularly in demotic texts. However, the civil months were frequently also known by individual names at this time. These names are theophorous in origin and can be traced back to the New Kingdom.

Although the name "Mesore" certainly represents the Egyptian Mswt ra, that name is almost never used in Egyptian; rather the month is called wpt rnpt -- "opener of the year". Both names are rather unexpected for the last month of the year, and the reason is a subject of debate. It appears to reflect the lunar month that straddled the end and the beginning of the civil year.

Additionally, the last five days of the year, which did not belong to any month, were known as "epagomenal days" or "Epagomene". These had individual names, as well as being numbered in the Epagomene:

The Year

The identity of an Egyptian civil year was usually identified by the regnal era of a king -- in principle, the number of years that had passed since the year of king's accession. Establishing the correct correlation of regnal eras is far and away the major source of complexity in the Egyptian calendar, as it is in ancient Egyptian chronology in general.

During the period covered by these tables, there were four systems of dating years, three of which operated simultaneously: an Egyptian civil year, an Egyptian financial year, a Macedonian regnal year, and an Augustan regnal year. The interactions between the first three of these systems result in many instances of double dated texts. The Macedonian year applied to the Macedonian calendar, and is not considered further here, except in the context of double dating.

Egyptian Civil Years

In Ptolemaic times, the Egyptian civil year was accounted from 1 Thoth. In the early reigns, the Egyptian civil year was used in Egyptian documents according to Egyptian custom, and was not the official regnal year. The official regnal year was determined according to the Macedonian calendar. This regnal year was used in Greek documents, especially official documents. However, by the time of Ptolemy V the two calendars had become closely aligned, to the point that the Macedonian calendar was subsumed into the Egyptian calendar. From this time on, the Egyptian civil year was also the official regnal year.

When one ruler succeeded another, the civil year number would change part way through the year, usually (though not always) from the old king's last year to year 1 of his successor. Thus the first civil year would be short, lasting only till the next 5 Epagomene. That is, in effect, the regnal era of a new ruler annexed the last year of his predecessor.

In principle, annexation should mean that year 1 of an incoming ruler is the same as the last year of his predecessor. In practice, a number of rulers (notably, Ptolemy II, Ptolemy VIII and Ptolemy X) accounted their reigns as starting before their actual accession. Ptolemy II may have changed the basis of his Egyptian regnal accounting part way through his reign, from an accession basis to a coregency basis, so that his Egyptian year 16 became year 18 and was followed immediately by year 19.

This xchange of system is now disputed, since there is some evidence that he used a coregency-based system from the beginning. To my knowledge a change of basis mid-reign is absolutely unique in Egyptian history (though Horemhab might have done something similar, if the Mes inscription dated to his year 59 is to be trusted). If you know better, please email me.

Additionally, at certain times (e.g. during periods of civil war) two different regnal eras were in use at the same time for a variety of reasons. Moreover, regnal eras which were not actually in use might still be accounted proleptically, e.g. years 8 to 24 of Ptolemy VIII which were actually years 19 to 35 of Ptolemy VI, so that retrospective dates may sometimes refer to these proleptic series. In some cases, e.g. the joint reign of Cleopatra III and Ptolemy X and the final years of Cleopatra VII, the two regnal series would be directly equated. These are shown as <A>=<B>. See further discussion below.

The evidence for the transitions between individual regnal eras are discussed under the genealogical entries for the rulers involved.

Egyptian Financial Years

From somewhere before year 23 in the reign of Ptolemy II at least through year 8 of Ptolemy IV, and probably to the start of the reign of Ptolemy V, the government operated a financial year that was based on the Egyptian civil calendar. As in modern financial years, the Ptolemaic financial year used the same calendar as the civil year but started on a different date. Under Ptolemy II, it ran from about 1 Mecheir to 30 Tybi; under later kings it seems to have started in Tybi. Although the system was invented for tax and accounting purposes, and was primarily used for this purpose, documents of a non-financial nature are known which incorporate financial year numbers. For this reason, care must be taken when converting dates dates from this period to ensure that they are not using the financial year.

Financial years were numbered similarly to ordinary civil years, but the transition between two consecutive financial years occurred on about 1 Mecheir (under Ptolemy II), or in Tybi (under later kings), not 1 Thoth. Therefore, in principle, the following relationships exist between a financial date and a civil date:

• If the king acceded between 1 Thoth and 30 Tybi, the financial date was the same as the civil date between 1 Thoth and 30 Tybi, and 1 year ahead of the civil date between 1 Mecheir and 5 Epagomene.
  

• If the king acceded between 1 Mecheir and 5 Epagomene, the financial date was the same as the civil date between 1 Mecheir and 5 Epagomene, and 1 year behind the civil date between 1 Thoth and 30 Tybi.

In practice, only the first relationship applied, since Ptolemy II evidently set up the system so that the financial year was ahead of the civil year, and since Ptolemy III and IV both succeeded early in the year. While the second syustem, in which the financial year lags behind the civil year, appears to have applied at the start of the reign of Ptolemy V, as far as I can determine (if you know better, please email me), there is no evidence that the system operated after the beginning of the reign of Ptolemy V.

The Alexandrian Calendar and Augustan Regnal Years

Augustus began his reign in Egypt by insitituting a regnal era based on the anniversary of the fall of Alexandria according to the Roman calendar (Kal. Sex. AUC 724 (30 B.C.) = 6 Mesore year 1). Thus, he did not annex the last year of Cleopatra VII, as was normal, and, in principle, the Egyptian date at which the year changed advanced by one day after every Roman leap year. Since a Roman leap day fell shortly after the annexation, years 2 to 4 began on 7 Mesore. However, since the Egyptian calendar did not have leap years, this system led to confusion at the beginning of year 5, when the start of the regnal year moved to 8 Mesore.

Probably because of this, at least in part, this system was abandoned at that time, by making year 5 last from Kal. Sex. AUC 728 (26 B.C.) = 8 Mesore year 5 to 5 Epagomene of the following year. Thereafter, Augustan years followed the traditional Egyptian pattern, but the year number was one less than would otherwise be customary. Since his death occurred very late in Mesore of year 43, the reign of Tiberius started in Thoth of the next year.

Retrospective references to dates in years 1 to 5 appear to be based on this system, except for the first 29 days of the reign. A date in this period was considered to be the Nth day of Caesar, as we know from an example in the Temple of Dendera (T. C. Skeat, CdE 69 (1994) 308).

Starting in year 5 of the reign of Augustus (=26/5), a leap day was inserted at the end of every fourth year, as a 6th epagomenal day; the first occurrence being at the end of year 9 = 22/1. This was regarded as a feast day for the imperial family: hmerai sebastai. The civil calendar so created is known as the Alexandrian calendar.

The effect of this reform was to fix the relationship between the civil year and the solar year (at least, to the same accuracy as the Julian year). Since the civil year had previously had no leap day, the Julian date corresponding to a given civil date had changed by one day every four years, a phenomenon that causes the pharaonic civil calendar to be known as the "wandering" year. The insertion of an additional day every four years created a fixed relationship between the Egyptian civil year and the Julian year. After the leap year cycle of the Roman year was finally synchronised to the Julian year, which was effective from 1 March 1 B.C., this relationship also applied to the Roman calendar. However, the wandering year continued to be used during the Roman period alongside the Alexandrian year.

Double Dates

Given the multiplicity of calendars and regnal dating systems, it is not surprising that double dates are frequently encountered in this period. There are at least eight double-dating systems documented in the literature.

Cross-calendrical double dates

The first four double-dating systems represent double dates between two different calendars. They are:

1. Macedonian / Egyptian double dates.

These typically take the form <Macedonian date> year N = <Egyptian date> and occur throughout the Ptolemaic era, starting around year 21 of Ptolemy II. The regnal year is almost always an official, Macedonian regnal year, though on occasion there may be grounds to suppose it was a financial year. After the assimilation of the Macedonian calendar at the start of the reign of Ptolemy V, the relationship of the Macedonian months to Egyptian months was fixed, and, with only five known exceptions (one of which is given by the Rosetta Stone), the day number in the Macedonian date is almost always equal to that of the Egyptian date.

2. Civil / financial double dates

These are found in tax and accounting documents. They typically take the form <Egyptian date> year N = year N+1 for dates after the strart of the financial year. Alternately, the document will be dated in Greek and demotic, with the Greek version naming year N+1 and the demotic year N. The first year is an Egyptian civil year, the second a financial year. They are known from Ptolemy II to the beginning of the reign of Ptolemy V.

3. Civil / lunar double dates

These typically take one of three forms:

• Complete synchronisms to civil dates: year N month X Day Y = (lunar) month X day Z (where Z < Y) or (lunar) month X-1 day Z (where Z > Y).
  

• Partial synchronisms to civil dates: year N month X Day Y = (lunar) day Z.
  
• Implied synchronisms inferred from dates of temple duty rosters, which were assigned by lunar months.

The earliest such double date known from Ptolemaic times is from year 10 of Ptolemy III = 237. They are known down to the reign of Cleopatra VII.

4. Civil / wandering double dates

During the Roman period, documents were sometimes double dated according to both the wandering and Alexandrian calendars. These dates typically take the form <Alexandrian Date> = <Wandering Date> Egyptian ("Aigup(tion)") or <Wandering Date> Old ("arcaiouV").

In principle, the distance between the two dates is a direct measure of the number of intercalations, or equivalently, the number of complete quadrennia that have elapsed since 5 Epagomene year 5 of Augustus = 29 August 26, because the wandering year gained an additional day against the Alexandrian calendar through intercalation every four years after that date. However, examples exist where only the month relationship is correct.

Double year numbers

The second four double-dating systems all represent double dates between two regnal eras which operated concurrently within the Egyptian civil calendar. The differences represent the reasons for the existence of the second era. They are:

1. Dual regnal series

These represent a single ruler who simultaneously operated two regnal eras, one on Egypt, the other in Syria. There are two such eras:

• year 36 = 1: Ptolemy VI as king of Egypt and Syria. This series only lasted a few months.
  

• year 16 = 1 to year 22 = 7: Cleopatra VII as king of Egypt and in Syria. At this time, year 16 = 1 is undocumented.

Year 36 = 1 of Ptolemy VI can (just) be distinguished from Year 36 = 1 of Ptolemy IX and Berenice III since the latter is not yet recorded before 28 Epeiph while the former is documented in Payni and was complete before 11 Epeiph.

2. Dual rulers

These represent a pair of rulers who, at least notionally, reigned simultaneously on different regnal eras, either in coregency or in opposition. There are five series:

• year 1 = 39 to year 5 = 43: Cleopatra II in opposition to Ptolemy VIII; only documented for years 1 = 39 and 2 = 40.
  

• year 11 = 8 to year 17 = 14: Cleopatra III and Ptolemy X; occasionally the dates are given in reverse order
  
• year 36 = 1 to year 37 = 2: Ptolemy IX and Berenice III; only year 36 = 1 is currently documented.
  
• year 1 = 23 to year 4 = 26: Ptolemy XII and Berenice IV; Ptolemy XII was not in fact ruling.
  
• year 1 = 3: (probably) Cleopatra VII in opposition to Ptolemy XIII; this series only lasted a few months.

Year 36 = 1 of Ptolemy IX and Berenice III can (just) be distinguished from Year 36 = 1 of Ptolemy VI since the former is not yet recorded before 28 Epeiph while the latter is documented in Payni and was complete before 11 Epeiph.

In practice, if perhaps not in theory, the rulers of these dual dates were always male/female pairs. One other case is known on the Macedonian calendar, equating regnal years of Alexander IV to satrapal years of Ptolemy I.

3. Transitional double dates

These represent the final year of an outgoing ruler equated with the first year of an incoming ruler. They take the form year <outgoing> = year <incoming>. They are documented for most regnal transitions after the death of Ptolemy VI:

• year 36 = 25: Transition from Ptolemy VI to the final reign of Ptolemy VIII
  

• year 26 = 29 and year 27 = 30: The long transition from Ptolemy X to Ptolemy IX (second reign)
  
• year 2 = 1: Transition from Berenice III to Ptolemy XII
  
• year 30 = 1: Transition from Ptolemy XII to Cleopatra VII and Ptolemy XIII

It appears that this type of transition originally occurred when the incoming ruler succeed in a year that was not year 1 of his (or her) claim to a regnal era. This is presumably why we have not found any examples of year 54 = 1 on the death of Ptolemy VIII.

The remaining transition of this type which is expected but is not yet documented, to my knowledge, is year 37 = 2, the transition from Ptolemy IX to Berenice III.

4. Retrospective double dates

These represent retrospective references made using one regnal era to years, which were proleptically covered by that era, equating them to the year numbers in the regnal era that was actually in use at the time. They take the form year <actual> = year <proleptic>.

The only instances I know are retrospective references under Ptolemy VI to dates between year 1 = 12 and year 7 = 18, which are actual years of Ptolemy VIII, from the period of his joint rule of Ptolemy VI, equated to proleptic years of Ptolemy VI reigning alone. Known examples range from year 1 = 12 to year 4 = 15.

It has been argued that similar retrospective double dates exist for actual years of Ptolemy VI against proleptic years of Ptolemy VIII. The two examples cited to date are for years 20 = 9 and [21] = 10. However, both have been misread. They should be assigned, respectively, to year 20 = 5 in the dual regnal era of Cleopatra VII, and, most probably, year [9] = 1<2> in the dual era of Ptolemy X and Cleopatra III.

Astronomical Eras

Although almost all documents from the period are dated by regnal eras of one type or another, there are several Egyptian eras that appear exclusively in astronomical documents, best known from the Almagest of Claudius Ptolemy.

1. The Era of Nabonassar

The Era of Nabonassar is a proleptic pseudo-regnal era starting on 1 Thoth year 1 of Nabonassar king of Babylon = 26 February 747. Ptolemy, Almagest 3.7, explains that this is the era from which ancient observations were preserved, more or less intact, to his own time.

Ptolemy, Almagest 4.11, quoting Hipparchus, notes that a series of Bablyonian eclipse records were "brought over" from Babylon to Athens. The sixth century scholiast Simplicius, In Aristotelis de caelo commentaria 6, states that the Bablyonian astronomical diaries were translated and sent to Athens by Alexander's scientific advisor Callisthenes of Olynthus. As Jona Lendering notes here, the truth of the scholium is established by the fact that Simplicius "correctly translates the Babylonian title of the diaries, massartu, with têrêseis, which is illogical in Greek but keeps the double meaning of 'guarding' and observing'".

It is not clear whether the Era of Nabonassar existed before Ptolemy's use of it in the second century AD, and it is generally believed that he invented it. However, the Canon of Ptolemy on which it is based certainly existed in Ptolemaic times, and must have been used to align the original Babylonian dates with the Egyptian calendar. Since the Era of the Death of Alexander was already in use by Hipparchus, according to Hipparchan dates quoted by Ptolemy, it would not surprise me if the Nabonassar Era also turned out to be a much older invention.

2. The Era of the Death of Alexander (Era of Philip)

The Era of the Death of Alexander is a proleptic pseudo-regnal era starting on 1 Thoth in the year Alexander the Great died = 12 November 324. In Ptolemy's Handy Tables, for which we have the fourth century edition of Theon of Alexandria, this era is renamed as the Era of Philip, Alexander's brother and successor. It is known to Censorinus 21.9 under this name.

This era occasionally appears in the Almagest for obversations made by Hipparchus, and Ptolemy (or his source) occasionally translates observational dates from the Era of Dionysios into this era. The fact that it appears in Hipparchan dates sugest that it was in use in Hipparchus' lifetime, although most Hipparchan dates are Callippic.

3. The Era of Dionysios

The Era of Dionysios is known solely from the Almagest, and was apparently only used in the third century, during the reigns of Ptolemy II and Ptolemy III. Although not actually an era of the Egyptian civil calendar, it apparently uses a calendar with zodiacally-named months that has almost the same structure as the Egyptian calendar: 11 months each of 30 days followed a final month of 35 or 36 days (or perhaps a 12th month of 30 days followed by 5 or 6 epagomenal days). It is based on a purely solar year of 365.25 days, anticipating both the Canopic and Augustan reforms. The era is based on the accession of Ptolemy II to the coregency.

Ptolemy translates the 7 Dionysian observations into Nabonassar dates. From these, and from the observational detail provided, we can establish synchronisms to the Julian calendar as follows:

• 25 Aigon (Capricorn) year 13 = 17/18 January 272
  

• 22 Scorpion (Scorpio) year 21 = 14/15 November 265
  
• 21 Hydron (Aquarius) year 23 = 11/12 February 262
  
• 4 Tauron (Taurus) year 23 = 25/26 April 262
  
• 28 Leonton (Leo) year 24 = 23 August 262
  
• 7 Didymon (Gemini) year 28 = 28/29 May 257
  
• 10 Parthenon (Virgo) year 45 = 3/4 September 241

This data was first analysed by A. Böckh in 1863. B. L. van der Waerden, AHES 29 (1984) 125, confirmed Böckh's analysis, showing that the synchronisms are consistent with a calendar based on a solar year of 365.25 days, with a leap day at the end of every year 4n+3, i.e. an intercalary cycle of phase 3. The year most probably started on the summer solstice, and the months were of 30 days each, except for the last month, Didymon (Gemini), which had 35 days, or 36 in a leap year (unless the extra 5 or 6 days were treated as epagomenal days in the Egyptian manner).

On this basis, the epoch of the Dionysian Era is 1 Karkinon (Cancer) year 1 = 26 June 285, which matches the coregency regnal era of Ptolemy II. Because of the phase difference between the Dionysian and Julian intercalary cycles, Dionysian years 4n start on 27 June, but 4n+1 - 4n+3 start on 26 June. This reconstruction has recently been strikingly confirmed by some scholia on the Almagest, probably from the sixth century A.D., published by A. Jones, Centaurus 45 (2003) 69. These state explicitly that the months were named after the zodiac signs, that they were of 30 days each, and that the year began on the summer solstice.

However, Jones cautions that these statements reflect the understanding of whoever converted the Dionysian dates into Egyptian ones, and probably do not reflect Dionysios' actual calendar, since "several of the observations do not best fit the Egyptian dates to which Ptolemy (sic?) assigns them." A. Jones, Ann. Sci. 63 (2006) 255 discusses these observation in detail, and shows that three of the seven Dionysian observations were off by one or two days, both early and late. He suggests that the actual Dionysian calendar was a parapegmatic calendar, similar to the calendar of Geminus. Geminus, Elementa Astronomiae, published a solstice-based zodiacal calendar with months of lengths 31, 31, 30, 30, 30, 29, 29, 30, 30, 31, 32, 32 days, incorporating observations dating back to Euctemon in the 5th century. Similar calendars, with different epochs and month-lengths, are known from Varro, Columella and others. Specifically, while noting that other solutions are certainly possible, Jones suggested (Ann. Sci. 63 (2006) 255 at 288) a calendar which Rehm had inferred as a Callipic calendar: months of lengths 31, 31, 30, 30, 30, 29, 30, 30, 30, 31, 31, 32 days (the difference from Geminus being highlighted).

4. The Egyptian Callippic Cycle

The Callippic Cycle is the most important of the astronomical eras for chronological purposes, since it appears to have had the most widespread use.

It is an astronomical cycle invented by the Athenian astronomer Callippus, probably from the Babylonian data sent to Athens by Callisthenes. It is a refinement of the Metonic cycle of 6940 days in which 235 lunar months fits almost exactly into 19 solar years. Since 19 solar years of 365.25 days each gives 6939.75 days, which is not an integral number of days, the Callippic cycle is a 76 year cycle equivalent to 4 Metonic cycles less 1 day. The cycle was used by Hipparchus and other Hellenistic astronomers, and the dates of a number of astronomical observations are recorded according to it in the Almagest of Claudius Ptolemy. From these observations it can be shown that year 1 of the First Callippic cycle began on the summer solstice of 330, which was a new moon. This is confirmed by two of Hipparchus' equinoctal observations that are dated to both year 32 of the Third Callipic Cycle and year 178 from the death of Alexander.

Dates within a Callippic cycle are either given in an astronomical Athenian calendar, which are then converted to their Egyptian equivalents, or directly as Egyptian dates, apparently according to the convention used by Ptolemy's source. The latter convention was used by the second century astronomer Hipparchus. The Hipparchan equinoctal observations (Almagest 3.1) place the boundary of the Callippic year at the summer solstice (or on the first new moon thereafter, Athenian-style). However, he also reports three lunar eclipses observed at Alexandria in 201 and 200 (Almagest 4.11), whose dates are given directly as Egyptian dates in the 54th and 55th years of the second Callippic cycle. A. Jones, ZPE 129 (2000) 141, showed that the year involved with these observations was the Egyptian civil year beginning in the Athenian year, since the two eclipses in year 55 were before and after the summer solstice, the year boundary in the Athenian version of the cycle. The same convention would explain a solar positional observation by Hipparchus (Almagest 5.3) on 16 Epeiph of year 50 of the Third Callippic Cycle = 5 August 128 by modern calculations; on the solstice-based year it should be year 51.

Until recently Callippic dates were not known outside the Almagest. However, in the same article, Jones noted that the newly-published papyrus pOxy 61.4137 was a fragment of a lunar eclipse canon from the first century AD recording candidate eclipse dates in the Sixth Callippic cycle. Based on this analysis, he was able to show that two other astronomical documents dated according to hitherto unidentified eras were actually using Callippic dates:

• Astronomical papyrus pdem Berlin 13146+13147 contains a series of Egyptians dates of equinoctes, solstices and observed and predicted lunar eclipses in years 17 to 32 of an unknown era. O. Neugebauer et al., Proc. Am. Phil. Soc. 125 (1981) 312, showed from the astronomical data that the events described took place between 85 and 69. A. Jones, ZPE 129 (2000) 141 identified the era as the years of the Fourth Callippic cycle. In this case, the years were not aligned to the Egyptian year.

• A. Jones, CdE 68 (1993) 178, had shown that the planetary alignments of the astronomical almanac Tab. Amst. inv. 1, given by Egyptian dates in years 1 and 2 of an unknown era, were those of 26/5 and 25/4. A. Jones, ZPE 129 (2000) 141 showed that these are years 1 and 2 of the Fifth Callippic Cycle.

While no other documents are presently known using this era, now that three have been identified it seems likely that there will be more. Moreover, its significance is not entirely technical. pdem Berlin 13146+13147 confirms directly that the Egyptian calendar had the expected alignment to the Julian calendar in the first century, while Tab. Amst. inv. 1 highlights the fact that the Alexandrian reform took effect in year 1 of a Callippic cycle, which might suggest that the Callippic era directly influenced its design.

An ephemeris calculator according to the principles of the Almagest which can provide calendar conversions to Callippic dates is available here.

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