Roman calendar

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For the Catholic liturgical calendar, see General Roman Calendar.
A reproduction of the fragmentary Fasti Antiates Maiores (c. 60 BC), with the seventh and eighth months still named Quintilis ("QVI") and Sextilis ("SEX") and an intercalary month ("INTER") in the far righthand column
Museum of the Roman Theater of Caesaraugusta in Zaragoza, Spain
Another reproduction of the Fasti Antiates Maiores

The Roman calendar is the calendar used by the Roman kingdom and republic. It is often inclusive of the Julian calendar established by the reforms of the dictator Julius Caesar and emperor Augustus in the late 1st century BC and sometimes inclusive of any system dated by inclusive counting towards months' kalends, nones, and ides in the Roman manner. It is usually exclusive of the Alexandrian calendar of Roman Egypt, which continued the unique months of that land's former calendar; the Byzantine calendar of the later Roman Empire, which usually dated the Roman months in the simple count of the ancient Greek calendars; and the Gregorian calendar, which refined the Julian system to bring it into still closer alignment with the solar year and is the basis of the current international standard.

Roman dates were counted inclusively forward to the next of three principle days: the first of the month (the kalends), a day less than the middle of the month (the ides), and eight days—nine, counting inclusively—before this (the nones). The original calendar consisted of 10 months beginning in spring with March; winter was left as an unassigned span of days. These months ran for 38 nundinal cycles, each forming a kind of eight (i.e., "nine") day week ended by religious rituals and a public market. The winter period was then used to create January and February. The legendary early kings Romulus and Numa were traditionally credited with establishing this early fixed calendar, which bears traces of its origin as an observational lunar one. In particular, the kalends, nones, and ides seem to have derived from the first sighting of the crescent moon, the first-quarter moon, and the full moon respectively. The system ran well short of the solar year, and it needed constant intercalation to keep religious festivals and other activities in their proper seasons. For superstitious reasons, this was kept in the middle of February even after it was no longer considered the last month.

After the establishment of the Roman Republic, years began to be dated by consulships and control over intercalation was granted to the pontifices, who eventually abused their power by lengthening years controlled by their political allies and shortening the years in their rivals' terms of office. Having won his war with Pompey, Caesar used his position as Rome's chief pontiff to enact a calendar reform in 46 BC, coincidentally making the year of his third consulship last for 446 days. In order to avoid interfering with Rome's religious ceremonies, the reform added all its days towards the ends of months and did not adjust any nones or ides, even in months which came to have 31 days. The Julian calendar was supposed to have a single leap day on 24 February (a doubled VI Kal. Mart.) every fourth year but following Caesar's assassination the priests figured this using inclusive counting and mistakenly added the bissextile day every three years. In order to bring the calendar back to its proper place, Augustus was obliged to suspend intercalation for a few decades. The revised calendar remaining slightly longer than the solar year, the date of Easter shifted far enough away from the vernal equinox that Pope Gregory XIII ordered its adjustment in the 16th century.


The remains of the Fasti Praenestini

Prehistoric lunar calendar[edit]

The original Roman calendar is believed to have been an observational lunar calendar[1] whose months began from the first signs of a new crescent moon. Because a lunar cycle is about 29½ days long, such months would have varied between 29 and 30 days. Twelve such months would have fallen 10 or 11 days short of the solar year; without adjustment, such a year would have quickly rotated out of alignment with the seasons in the manner of the present-day Islamic calendar. Given the seasonal aspects of the later calendar and its associated religious festivals, this was presumably avoided through some form of intercalation or through the suspension of the calendar during winter.

Legendary 10-month calendar[edit]

The Romans themselves described their first organized year as one with ten fixed months, each of 30 or 31 days.[2][3] Such a decimal division fit general Roman practice.[4] The four 31-day months were called "full" (pleni) and the others "hollow" (cavi).[a][6] Its 304 days made up exactly 38 nundinal cycles. The system is usually said to have left the remaining 50-odd days of the year as an unorganized "winter", although Licinius Macer's lost history apparently stated the earliest Roman calendar employed intercalation instead[7][8] and Macrobius claims the 10-month calendar was allowed to shift until the summer and winter months were completely misplaced, at which time additional days belonging to no month were simply inserted into the calendar until it seemed things were restored to their proper place.[9][10]

Later Roman writers credited this calendar to Romulus,[11][12] their legendary first king and culture hero, although this was common with other practices and traditions whose origin had been lost to them. Some scholars doubt the existence of this calendar at all, as it is only attested in late Republican and Imperial sources and apparently supported only by the misplaced names of the months from September to December.[13] Rüpke also finds the coincidence of the length of the supposed "Romulan" year with the length of the first ten months of the Julian calendar to be suspicious.[13]

"Calendar of Romulus"
English Latin Meaning Length
in days
March Mensis Martius Month of Mars 31
April Mensis Aprilis Uncertain 30
May Mensis Maius Uncertain 31
June Mensis Iunius Month of Juno 30
Quintilis Mensis Quintilis
Mensis Quinctilis[14]
Fifth Month 31
Sextilis Mensis Sextilis Sixth Month 30
September Mensis September Seventh Month 30
October Mensis October Eighth Month 31
November Mensis November Ninth Month 30
December Mensis December Tenth Month 30

Other traditions existed alongside this one, however. Plutarch's Parallel Lives recounts that Romulus's calendar had been solar but adhered to the general principle that the year should last for 360 days. Months were employed secondarily and haphazardly, with some counted as 20 days and others as 35 or more.[15][16]

Republican calendar[edit]

The attested calendar of the Roman Republic was quite different. It followed Greek calendars in assuming a lunar cycle of 29½ days and a solar year of 12½ synodic months (368¾ days), which align every fourth year after the addition of two intercalary months.[6] The additional two months of the year were January and February; the intercalary month was sometimes known as Mercedonius.[6]

The Romans did not follow the usual Greek practice in alternating 29- and 30-day months and a 29- or 30-day intercalary month every other year. Instead, their 3rd, 5th, 7th, and 10th months[b] had 31 days each; all the other months had 29 days except February, which had 28 days for three years and then 29 every fourth year. The total of these months over a 4-year span differed from the Greeks by 5 days, meaning the Roman intercalary month always had 27 days. Similarly, within each month, the weeks did not vary in the Greek fashion between 7 and 8 days; instead, the full months had two additional days in their first week and the other three weeks of every month ran for 8 days ("nine" by Roman reckoning).[17] Still more unusually, the intercalary month was not placed at the end of the year but within the month of February after the Terminalia on the 23rd (a.d. VII Kal. Mart.); the remaining days of February followed its completion. This seems to have arisen from Roman superstitions concerning the numbering and order of the months.[citation needed] The arrangement of the Roman calendar similarly seems to have arisen from Pythagorean superstitions concerning the luckiness of odd numbers.[17]

These Pythagorean-based changes to the Roman calendar were generally credited by the Romans to Numa, Romulus's successor and the 2nd of Rome's 7 kings,[citation needed] as were the two new months of the calendar.[18][19][c] Most sources thought he had established intercalation with the rest of his calendar.[citation needed] Although Livy's Numa instituted a lunar calendar, the author claimed the king had instituted a 19-year system of intercalation equivalent to the Metonic Cycle[20] centuries before its development by Babylonian and Greek astronomers.[d] Plutarch's account claims he ended the former chaos of the calendar by employing 12 months totaling 354 days—the length of the lunar and Greek years—and biennial intercalary months of 22 days.[15][16]

Plutarch believed Numa was responsible for placing January and February first in the calendar;[15][16] Ovid states January began as the first month and February the last, with its present order owing to the Decemvirs.[22][23] Fowler believed the Roman priests continued to treat January and February as the last months of the calendar throughout the Republican period.[24]

Pre-Julian Roman Calendar
English Latin Meaning Length
in days
January Mensis Ianuarius Month of Janus 29
February Mensis Februarius Month of the Februa 28
Intercalary Month Mercedonius Month of Wages 23
March Mensis Martius Month of Mars 31
April Mensis Aprilis Uncertain 29
May Mensis Maius Uncertain 31
June Mensis Iunius Month of Juno 29
Quintilis Mensis Quintilis
Mensis Quinctilis[14]
Fifth Month 31
Sextilis Mensis Sextilis Sixth Month 29
September Mensis September Seventh Month 29
October Mensis October Eighth Month 31
November Mensis November Ninth Month 29
December Mensis December Tenth Month 29

Flavian reform[edit]

Gnaeus Flavius, a secretary to the pontifex maximus, introduced a series of reforms in 304 BC. Their exact nature is uncertain, although he is thought to have begun the custom of publishing the calendar in advance of the month, depriving the priests of some of their power but allowing for a more consistent calendar for official business.[27]

Julian reform[edit]

Main article: Julian calendar

Julius Caesar, as Pontifex Maximus, reformed the calendar in 46 BC. The new calendar became known as the Julian calendar. Quintilis was renamed Iulius (July) in honour of Julius Caesar in 44 BC[citation needed] by Mark Antony. A further change was made during the reign of his successor Augustus, when, apparently following the Senate, the plebiscite Lex Pacuvia de mense augusto renamed Sextilis Augustus (August) in 8 BC.[28][29] Some documents state that the date of the change of the name started between 26 and 23 BC but the date of the Lex Pacuvia is certain.[citation needed]


The regular calendar had only 355 days, which meant that it would quickly be unsynchronized with the solar year, causing, for example, agricultural festivals to occur out of season. The Roman solution to this problem was to periodically lengthen the calendar by adding extra days to February. February consisted of two parts, each with an odd number of days. The first part ended with the Terminalia on the 23rd, which was considered the end of the religious year, and the five remaining days formed the second part. To keep the calendar year roughly aligned with the solar year, a leap month, called the Mensis Intercalaris ("intercalary month"), was added from time to time between these two parts of February. The second part of February was incorporated in the intercalary month as its last five days, with no change either in their dates or the festivals observed on them. This follows naturally from the fact that the days after the Ides of February (in an ordinary year) or the Ides of Intercalaris (in an intercalary year) both counted down to the Kalends of March. The nones and ides of Intercalaris occupied the normal positions of the 5th and 13th of the month.

The third-century writer Censorinus says:

When it was thought necessary to add (every two years) an intercalary month of 22 or 23 days, so that the civil year should correspond to the natural (solar) year, this intercalation was in preference made in February, between Terminalia [23rd] and Regifugium [24th].[30]

The fifth-century writer Macrobius says that the Romans intercalated 22 and 23 days in alternate years (Saturnalia, 1.13.12), the intercalation was placed after 23 February and the remaining five days of February followed (Saturnalia, 1.13.15). To avoid the nones falling on a nundine, where necessary an intercalary day was inserted "in the middle of the Terminalia, where they placed the intercalary month".[25]

This is historically correct. In 167 BC Intercalaris began on the day after 23 February [31] and in 170 BC it began on the second day after 23 February.[32] Varro, writing in the first century BC, says "the twelfth month was February, and when intercalations take place the five last days of this month are removed."[33] Since all the days after the Ides of Intercalaris were counted down to the beginning of March Intercalaris had either 27 days (making 377 for the year) or 28 (making 378 for the year).

There is another theory which says that in intercalary years February had 23 or 24 days and Intercalaris had 27. No date is offered for the Regifugium in 378-day years.[34] Macrobius describes a further refinement whereby, in one 8-year period within a 24-year cycle, there were only three intercalary years, each of 377 days. This refinement brings the calendar back in line with the seasons, and averages the length of the year to 365.25 days over 24 years.

The Pontifex Maximus determined when an intercalary month was to be inserted. On average, this happened in alternate years. The system of aligning the year through intercalary months broke down at least twice: the first time was during and after the Second Punic War. It led to the reform of the Lex Acilia in 191 BC, the details of which are unclear, but it appears to have successfully regulated intercalation for over a century. The second breakdown was in the middle of the first century BC and may have been related to the increasingly chaotic and adversarial nature of Roman politics at the time. The position of Pontifex Maximus was not a full-time job; it was held by a member of the Roman elite, who would almost invariably be involved in the machinations of Roman politics. Because the term of office of elected Roman magistrates was defined in terms of a Roman calendar year, a Pontifex Maximus would have reason to lengthen a year in which he or his allies were in power, or shorten a year in which his political opponents held office.

Although there are many stories to interpret the intercalation, a period of 22 or 23 days is always 3/4 synodic month. Obviously, the month beginning shifts forward (from the new moon, to the third quarter, to the full moon, to the first quarter, back the new moon) after intercalation.


The origins of the names of the months are not entirely clear or agreed upon by modern scholars. Some ancient explanations are: Martius in honour of Mars, the god of war; Aprilis from aperiō, to open: Earth opens to receive seed; Maius from Maia, goddess of growth (maior, elder); Iunius from iunior (younger). The remaining six months were named with respect to their position on the calendar: the numbers five to ten in Latin being quinque, sex, septem, octo, novem and decem, the months were named Quintilis, Sextilis, September, October, November, and December.

In the earliest times, the three reference dates were probably declared publicly, when appropriate lunar conditions were observed. After the reforms of Numa, they occurred on fixed days.

  • Kalendae (whence "calendar"), Kalends—first day of the month; it is thought to have originally been the day of the new moon. According to some ancient or modern proposed etymologies of the word, it was derived from the phrase kalo Iuno Covella or kalo Iuno Novella, meaning, respectively, "hollow Juno I call you" and "new Juno I call you", an announcement about the Nones or in proclaiming the new moon that marked the Kalends which the pontiffs made every first day of the month on the Capitoline Hill in the Announcement Hall.[35][36]
  • Idus or Eidus, Ides—thought to have originally been the day of the full moon, was the 15th day of March, May, July, and October (the months with 31 days) and the 13th day of the other months.
  • Nonae, Nones—thought to have originally been the day of the half moon. The Nones was eight days before the Ides, and fell on the fifth or seventh day of the month, depending on the position of the Ides. (Nones implies ninth from the Latin novem, because, counting Ides as first, one day before is the second, and eight days before is the ninth).

The day preceding the Kalends, Nones, or Ides was Pridie, e.g., Prid. Id. Mart. = 14 March. Other days were denoted by ordinal number, counting back from a named reference day. The reference day itself counted as the first, so that two days before was denoted the third day. Dates were written as a.d. NN, an abbreviation for ante diem NN, meaning "on the Nth (Numerus) day before the named reference day (Nomen)",[37] e.g., a.d. III Kal. Nov. = on the third day before the November Kalends = 30 October. The value two was not used to denote a day before the fixed point, because second was the same as pridie. Further examples of date equivalence are: a.d. IV Non. Jan. = 2 January; a.d. VI Non. Mai. = 2 May; a.d. VIII Id. Apr. = 6 April; a.d. VIII Id. Oct. = 8 October; a.d. XVII Kal. Nov. = 16 October.

In detail, the system worked as follows:

Months were grouped in days such that the Kalends was the first day of the month, the Ides was the 13th day of short months, or the 15th day of long months, and the Nones was the 9th day (counted inclusively) before the Ides (i.e., the fifth or seventh day of the month). All other days of the month were counted backward (inclusively) from these three dates. In both long and short months (except February and the mensis intercalaris) there were 16 days between the Ides of the month and the Kalends of the next month, and the date referred to the name of the next month, not that of the current month; thus, for example, the date of the 16th day of March was a.d. XVII Kal. Apr. In intercalary years, the first part of February was terminated on the 23rd, i.e., the day of the Terminalia, and the festivals normally held in the last five days of February were held instead in the last five days of the intercalary month, immediately before the Kalends of March. The first 22 or 23 days of the intercalary month were inserted between these two parts.


  • In long months (31 days—March, May, July (Quintilis), and October), the days were divided into:
    • 1st day of the month: 1 day for the Kalends of the month
    • 2nd to 6th days of the month: 5 days before the Nones
    • 7th day of the month: 1 day for the Nones
    • 8th to 14th days of the month: 7 days before the Ides
    • 15th day of the month: 1 day for the Ides
    • 16th to 31st days of the month: 16 days before the Kalends of the next month
  • In short months (29 days—January, April, June, August (Sextilis), September, November and December), the days were divided into:
    • 1st day of the month: 1 day for the Kalends of the month
    • 2nd to 4th days of the month: 3 days before the Nones
    • 5th day of the month: 1 day for the Nones
    • 6th to 12th days of the month: 7 days before the Ides
    • 13th day of the month: 1 day for the Ides
    • 14th to 29th days of the month: 16 days before the Kalends of the next month
  • In ordinary years, the days in February (28 days) were divided into:
    • 1st day of the month: 1 day for the Kalends of February
    • 2nd to 4th days of the month: 3 days before the Nones
    • 5th day of the month: 1 day for the Nones
    • 6th to 12th days of the month: 7 days before the Ides
    • 13th day of the month: 1 day for the Ides
    • 14th to 28th days of the month: 15 days before the Kalends of March
  • In intercalary years, the days in February (23 days) were divided into:
    • 1st day of the month: 1 day for the Kalends of February
    • 2nd to 4th days of the month: 3 days before the Nones
    • 5th day of the month: 1 day for the Nones
    • 6th to 12th days of the month: 7 days before the Ides
    • 13th day of the month: 1 day for the Ides
    • 14th day onwards: counting down to a festival (see below) or to the Kalends of the intercalary month
  • The days of the intercalary month inserted in intercalary years (27 days) were divided into:
    • 1st day of the intercalary month: 1 day for the Kalends of the intercalary month
    • 2nd to 4th days of the intercalary month: 3 days before the Nones
    • 5th day of the intercalary month: 1 day for the Nones
    • 6th to 12th days of the intercalary month: 7 days before the Ides
    • 13th day of the intercalary month: 1 day for the Ides
    • 14th day onwards: counting down to the Kalends of March

Some dates were also sometimes known by the name of a festival that occurred on them, or shortly afterwards. Examples of such dates are recorded for the Feralia, Quirinalia, and the Terminalia, though not yet for the Lupercalia. The known examples of such dates are all after the Ides of February, which suggests they are connected with resolving an ambiguity that could arise in intercalary years: dates of the form a.d. [N] Kal. Mart. were dates in late February in regular years, but were a month later in intercalary years. However, it is much debated whether there was a fixed rule for using festival-based dates. It has been variously proposed that a date like a.d. X Terminalia (known from an inscription in 94 BC) implied that its year 'was', 'was not', or 'might have been' intercalary.

When Julius Caesar added days to some of the months, he added them to the end of the month, so as not to disturb the dates of festivals in those months. This increased the count of all days after the Ides in those months, and had some odd effects. For example, the emperor Augustus was born in 63 BC on the 23rd day of September. In the pre-Julian calendar, this is seven days before the Kalends of October (or, in Roman style, counting inclusively, a.d. VIII Kal. Oct.), but in the Julian calendar, it is eight days (a.d. IX Kal. Oct.). Because of this ambiguity, his birthday was sometimes celebrated on both dates. See discussion in Julian calendar.

Nundinal cycle[edit]

A fragment of the Fasti Praenestini for the month of April (Aprilis), showing the nundinal letters on the left edge

The Romans of the Republic, like the Etruscans, used a "market week" of eight days, marked as A to H in the calendar. A nundinum was the market day; etymologically, the word is related to novem, "nine", because the Roman system of counting was inclusive. The market "week" is the nundinal cycle. Since the length of the year was not a multiple of eight days, the letter for the market day (known as a "nundinal letter") changed every year. For example, if the letter for market days in some year was A and the year was 355 days long, then the letter for the next year would be F.

The nundinal cycle formed one rhythm of day-to-day Roman life; the market day was the day when country people would come to the city, and the day when city people would buy their eight days' worth of groceries. For this reason, a law was passed in 287 BC (the Lex Hortensia) that forbade the holding of meetings of the comitia (for example to hold elections) on market days, but permitted the holding of legal actions. In the late republic, a superstition arose that it was unlucky to start the year with a market day (i.e., for the market day to fall on 1 January, with a letter A), and the pontiffs, who regulated the calendar, took steps to avoid it.

Because the nundinal cycle was absolutely fixed at eight days under the Republic, information about the dates of market days is one of the most important tools used for working out the Julian equivalent of a Roman date in the pre-Julian calendar. In the early Empire, the Roman market day was occasionally changed. The details of this are not clear, but one likely explanation put forward is that it would be moved by one day if it fell on the same day as the festival of Regifugium, an event that could occur at intervals of three years. The reason for this movement has not been explained.

The nundinal cycle was eventually replaced by the modern seven-day week, which first came into use in Italy during the early imperial period,[38] after the Julian calendar had come into effect in 45 BC. The system of nundinal letters was also adapted for the week. (See dominical letter.) For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted by Constantine in AD 321, the nundinal cycle had fallen out of use. For further information on the week, see week and days of the week.

Character of the day[edit]

Each day of the Roman calendar was marked on the fasti with a letter that designated its religious and legal character. These were:[39]

  • F (fastus), days when it was legal to initiate action in the courts of civil law (dies fasti);
  • C (comitialis), a day on which the Roman people could hold assemblies (dies comitalis);
  • N (nefastus), when these political activities and the administration of justice were prohibited (dies nefasti);
  • NP of elusive meaning, but marking feriae, public holidays (thought by some to mean nefastus priore, "unlawful before noon", along with FP, fastus priore, "lawful before noon");
  • QRCF (perhaps for quando rex comitiavit fas,[40] "Permissible, when the king has entered the comitium"), a day when it was religiously permissible for the rex (probably the priest known as the Rex Sacrorum) to call for an assembly;[41]
  • EN (endotercissus, an archaic form of intercissus, "cut in half"), for days that were nefasti in the morning, when sacrifices were being prepared, as well as in the evening, while sacrifices were being offered, but were fasti in the middle of the day.


Fragment of an imperial-age consular fasti, Museo Epigrafico, Rome

The calendar year originally began on 1 March, as is shown by the names of the six months following June (Quintilis = fifth month, Sextilis = sixth month, September = seventh month, etc.). It is not known when the start of the calendar year was changed to 1 January. Ancient authors attributed it to Numa Pompilius. Varro states that, according to M. Fulvius Nobilior (consul in 189 BC), who had composed a commentary on a fasti preserved in the temple of Hercules Musarum, January was named after Janus because the god faced both ways, which implies the calendar year started in January in his time, before the consular year started beginning on 1 January in 153 BC. A surviving calendar from the late Republic proves the calendar year started in January before the Julian reform.

How years were identified during the Roman monarchy is not known. During the Roman Republic, years were named after the consuls, who were elected annually (see List of Republican Roman Consuls). Thus, the name of the year identified a consular term of office, not a calendar year. For example, 205 BC was "The year of the consulship of Publius Cornelius Scipio Africanus and Publius Licinius Crassus", who took office on 15 March of that year, and their consular year ran until 14 March 204 BC. Lists of consuls were maintained in the fasti.

The first day of the consular term changed several times during Roman history. The Senate changed it to 1 January in 153 BC in order to allow consul Quintus Fulvius Nobilior to attack the city of Segeda (in Aragon, Spain) during the Celtiberian Wars.[42] Before then, it was 15 March. Earlier changes are a little less certain. There is good reason to believe it was 1 May for most of the third century BC, until 222 BC. Livy mentions earlier consular years starting on 1 Sextilis (August), 15 May, 15 December, 1 October and 1 Quintilis (July).

In the later Republic, historians and scholars began to count years from the founding of the city of Rome. Different scholars used different dates for this event. The date most widely used today is that calculated by Varro, 753 BC, but other systems varied by up to several decades. Dates given by this method are numbered ab urbe condita (meaning "from the founding of the city", and abbreviated AUC), and correspond to consular years. When reading ancient works using AUC dates, care must be taken to determine the epoch used by the author before translating the date into a Julian year.

In parts of the Roman empire, it was common to date by the provincial year (anno prouinciarium, A.PP.). In Roman Africa, year 1 was AD 39; in Hispania it was 38. Thus, to arrive at AD dates for Africa and Spain it is necessary to add 39 and 38, respectively, to the provincial year. The Spanish provincial year was the basis of the Spanish era, the dating system common throughout Spain during the Middle Ages.[43]

Extant fasti[edit]

A section of the Fasti Praenestini, with the entry on the "Feast of Robigo" (bottom right).

A considerable number of inscribed calendars, or fasti, have been discovered. The Praenestine calendar (Fasti praenestini), discovered in 1770, arranged by the famous grammarian Verrius Flaccus, contains the months of January, March, April, and December, and a portion of February. The tablets give an account of festivals, and also of the triumphs of Augustus and Tiberius. There are still two complete calendars in existence, an official list by Philocalus (354), and a Christian version of the official calendar, made by Polemius Silvius (448).

Converting pre-Julian dates[edit]

The fact that the modern world uses the same month names as the Romans can lead to an erroneous assumption that a Roman date occurred on the same Julian date as its modern equivalent. Even early Julian dates, before the leap year cycle was stabilised, are not quite what they appear to be. For example, Macrobius says 45 BC was not a leap year.

Finding the exact Julian equivalent of a pre-Julian date is complex. As there exists an essentially complete list of the consuls, a Julian year can be found to correspond to the pre-Julian year.

However, the sources rarely reveal which years were regular, which were intercalary, and how long an intercalary year was. Nevertheless, the pre-Julian calendar could be substantially out of alignment with the Julian calendar. Two precise astronomical synchronisms given by Livy show that in 168 BC, the two calendars were misaligned by more than two months, and in 190 BC, they were four months out of alignment.

A number of other clues are available to reconstruct the Julian equivalent of pre-Julian dates. First, the precise Julian date for the start of the Julian calendar is known, although some uncertainty occurs even about that. Detailed sources for the previous decade or so are found, mostly in the letters and speeches of Cicero. Combining these with what is known about how the calendar worked, especially the nundinal cycle, an accurate conversion of Roman dates after 58 BC relative to the start of the Julian calendar can be performed.

The histories of Livy give exact Roman dates for two eclipses in 190 BC and 168 BC, and a few loose synchronisms to dates in other calendars provide rough (and sometimes exact) solutions for the intervening period. Before 190 BC, the alignment between the Roman and Julian years is determined by clues such as the dates of harvests mentioned in the sources.

Combining these sources of data, an estimate can be computed for approximate Julian equivalents of Roman dates back to the start of the First Punic War in 264 BC. However, while there are enough data to make such reconstructions, the number of years before 45 BC for which pre-Julian Roman dates can be converted to Julian dates with certainty is very small, and several different reconstructions of the pre-Julian calendar are possible. A detailed reconstruction giving conversions from pre-Julian dates into Julian dates is available.[44]

See also[edit]


  1. ^ Censorinus, Macrobius, and Solinus, cited in Key.[5]
  2. ^ That is, the 1st, 3rd, 5th, and 8th months prior to the introduction and repositioning of January and February.
  3. ^ Plutarch reports this tradition while claiming that the months had more probably predated or originated with Romulus.[15][16]
  4. ^ This equivalence was first described by Stanyan in his history of ancient Greece.[21]



  1. ^ Mommsen & al. (1864), pp. 216.
  2. ^ a b Macrobius, Book I, Ch. 12, §3.
  3. ^ a b Kaster (2011), p. 137.
  4. ^ Mommsen & al. (1864), pp. 217.
  5. ^ Key (1875).
  6. ^ a b c Mommsen & al. (1864), p. 218.
  7. ^ Macrobius, Book I, Ch. 13, §20.
  8. ^ Kaster (2011), p. 165.
  9. ^ Macrobius, Book I, Ch. 12, §39.
  10. ^ Kaster (2011), p. 155.
  11. ^ Macrobius, Book I, Ch. 12, §§5 & 38.
  12. ^ Kaster (2011), pp. 137 & 155.
  13. ^ a b Rüpke (2011), p. 23.
  14. ^ a b Blackburn & al. (1999), p. 669.
  15. ^ a b c d e Plutarch, Ch. 18.
  16. ^ a b c d e Perrin (1914), pp. 368 ff.
  17. ^ a b Mommsen & al. (1864), p. 219.
  18. ^ Macrobius, Book I, Ch. 12, §34.
  19. ^ Kaster (2011), p. 153.
  20. ^ Roberts (1905), Book I, Ch. 19, §6.
  21. ^ Stanyan (1707), p. 330.
  22. ^ Ovid, Book II.
  23. ^ Kline (2004), Book II, Introduction.
  24. ^ Fowler (1899), p. 5.
  25. ^ a b Macrobius.
  26. ^ Kaster (2011).
  27. ^ Lanfranchi, Thibaud (3 October 2013), "À Propos de la Carrière de Cn. Flavius", Mélanges de l'École Française de Rome: Antiquité, Vol. 125 (No. 1), doi:10.4000/mefra.1322 . (French)
  28. ^ Rotondi, 1912, p. 441
  29. ^ Macrobius, Saturnalia, 1.12
  30. ^ Censorinus, The Natal Day, 20.28, tr. William Maude, New York 1900, available at [1].
  31. ^ Livy 45.44.3.
  32. ^ Livy 43.11.13.
  33. ^ Varro, On the Latin language, 6.13, tr. Roland Kent, London 1938, available at [2].
  34. ^ Michels (1967).
  35. ^ Varro, Marcus Terentius (1938). "VI.27". De lingua latina [On the Latin Language]. Loeb Classical Library (in Latin and English). I. Translated by Roland Grubb Kent. pp. 198–201.  At the Internet Archive. kalo or calo is a form of the verb calare, meaning "to announce solemnly", "to call out"; see Harper, Douglas. "calendar". Online Etymology Dictionary.  calare. Charlton T. Lewis and Charles Short. A Latin Dictionary on Perseus Project.
  36. ^ Rüpke (2011), p. 24–25.
  37. ^ Syntax note: The Romans often inserted a phrase between a preposition and its noun, and here. a.d. III Kal. Nov. (ante diem tertium Kalendas Novembres), ante governs Kalendas, and the literal meaning is 'on the third day' [diem tertium accusative of time] 'before the November kalends' [the month name is an adjective in Latin]. In late Latin, the 'a.d.' was sometimes dropped in favor of an ablative construction.
  38. ^ Brind'Amour (1983), pp. 256–275.
  39. ^ Unless otherwise noted, the explanations of the following abbreviations are from Howard Hayes Scullard, Festivals and Ceremonies of the Roman Republic (Cornell University Press, 1981), pp. 44–45.
  40. ^ On the basis of the Fasti Viae Lanza, which gives Q. Rex C. F.
  41. ^ Rüpke (2011), pp. 26–27.
  42. ^ Francisco Burillo, Segeda and Rome. The historical development of a Celtiberian city-state
  43. ^ Ralph W. Mathieson, People, Personal Expression, and Social Relations in Late Antiquity, vol. 2 (University of Michigan, 2003), pp. 14–15.
  44. ^ Roman Dates


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