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Roman Dates

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How to Read the Conversion Table

Each row in the conversion table corresponds to a Roman civil year, in principle identified by its Varronian year number. The Julian years corresponding to the first and last day of the corresponding Roman year are given on either side. The entries in the row give the Julian date for the start of each Roman month in the corresponding Julian year. Additionally, the nundinal letter(s) for the market day in each civil year are also given.

Finally, supplementary infomation useful for interpreting the tables is colour-coded, or encoded in the font style. The details of this is explained further below; see here for the colour coding of the body of the table.

Roman Month Names

The Roman month names are given across the top in the form used in the Republic. They are repeated on the boundary between years B.C. and A.D. in the form used in the early Empire. The following changes occurred in the period covered by the tables:

• Quintilis was renamed Iulius in A.U.C. 709 = 44.
  

• Sextilis was renamed Augustus in connection with the Augustan calendar reform of A.U.C. 746 = 8 B.C.
  
• September was renamed Germanicus on the accession of Caligula in A.U.C. 790 = A.D. 37, but reverted to September after a few years, probably on his death.
  
• Intercalaris is the occasional intercalary month of the Republican calendar. It was abolished in the Caesarian reform of A.U.C 708 = 46 B.C. The two intercalary months inserted after November of A.U.C 708 = 46 BC, whose individual lengths are unknown, are combined under the heading Int. I+II.

Equivalent Julian Years

The left hand column gives the Julian year B.C. in which the corresponding Roman year began. This may be the same as the Julian year usually equated with the Roman year, or one year earlier.

• If the Julian year is that which conventionally corresponds to the Roman civil year, the Julian year number is bolded.
  

• If 1 January of the corresponding Julian year fell after Kal. Ian. of the Roman civil year then the column gives the year before the conventional Julian year; this is signalled by italicising the year number.
  
• In some cases a Roman civil year completely subsumes a Julian year. In these cases the next Julian year entry changes by 2, not 1. This discontinuity is indicated by highlighting the next Julian year in red.
  
• Conversely, a Julian year may completely subsume a Roman civil year, so that the following Kal. Ian. will fall in the same Julian year, and the next Julian entry does not change value. This discontinuity is also indicated by highlighting the next Julian year in red.

The rightmost column but one gives the Julian year B.C. in which the corresponding Roman civil year ended. This may be the same as the Julian year usually equated with the Roman civil year, or one year later.

• If the Julian year is that which conventionally corresponds to the Roman civil year, the Julian year number is bolded.
  

• If 1 January of the corresponding Julian year fell before the end of the Roman civil year then the column gives the year after the conventional Julian year; this is signalled by italicising the year number.
  
• In some cases a Roman civil year completely subsumes a Julian year. In these cases the next Julian year entry changes by 2, not 1. This discontinuity is indicated by highlighting the next Julian year in red.
  
• Conversely, a Julian year may completely subsume a Roman civil year, so that the following Kal. Ian. will fall in the same Julian year, and the next Julian entry does not change value. This discontinuity is also indicated by highlighting the next Julian year in red.

Varronian Year

The second column gives the Varronian year number A.U.C. (ab urbe condita) for the Roman civil year on Kal. Ian., assuming that A.U.C. 1 = 753 B.C. The third column from the right gives the Varronian year number for the Roman civil year on Kal. Dec. The bolded Varronian year number is the number that identifies the civil year.

The two columns differ before A.U.C. 601 = 153 B.C. because the Varronian year is accounted as the consular year. The start of the consular year changed from time to time. It started on Id. Mart. before A.U.C. 601 = 153 and Kal. Ian. thereafter; AUC 600 was a short year running from Id. Mart. to prid. Kal. Ian. It is held here, as by most chronologists (though not by Brind'Amour) that it started on Kal. Mai. before A.U.C. 532 = 222. The Varronian year boundaries in the period before A.U.C. 601 are indicated by a blue line. During this period the second column gives the Varronian year applying on Kal. Ian, while the third-last column gives the Varronian year for the period Id. Mart. (or Kal. Mai.) to December, which is one year later.

The Varronian year is given here partly for convenience and partly because it is widely used by modern Roman chronologists. It was not ordinarily used by the Romans themselves at this time. Roman years were identified eponymously by the presiding consuls. Eponym lists, known as fasti consulares, were maintained by the Romans and survived into medieval times. These allow us accurately to date the year by consular name, although they are not considered fully reliable before about 300 B.C. An example of a complete list, including replacement ("suffect") consuls, is shown here.

Date Conversions

Each row entry in the main part of the first two tables gives the Julian date for the start of the corresponding Roman civil month in the applicable Varronian year.

The following colour conventions indicate the certainty of converted dates:

• Dates whose conversions are certain, because they are in a fixed calendrical relationship to a certain synchronism, are given in black.
  

• Pre-Julian dates whose conversions depend on the reconstructed Lex Acilia proposed here are given in brown.
  
• Pre-Julian dates whose conversions additionally depend on the assumption that a date in late Februarius which is constructed as a festival reference (e.g. a.d. III Feralia) indicates a candidate intercalary year are italicised. See discussion here.
  
• Pre-Julian dates whose conversions depend entirely on a nundinal datum are given in orange.
  
• Pre-Julian dates in magenta represent only one possible conversion -- in effect its a best guess.

The following colour conventions indicate synchronistic data in the corresponding month:

• Roman months for which there is an astronomical synchronism are given in red. Dates which are also bolded are precise eclipse synchronisms.
  

• Roman months for which loose synchronisms are known or argued in years where exact synchronisms or solutions are not otherwise available, or which help to establish exact synchronisms, are indicated in bold green. These synchronisms are sufficiently accurate to limit the number of intercalations in the period around the marked date.
  
• Roman months for which there is a synchronism to another calendar are indicated in bolded violet. These synchronisms are sufficiently accurate to limit the number of intercalations in the period around the marked date.
  
• Roman months for which data exists that places restrictions on the nundinal cycle are indicated in bold orange. These months either contain known nundinal dates or known comitial dates.

The following colour conventions apply to cell backgrounds:

The following additional colour conventions apply:

• In the period A.U.C. 492 = 262 to A.U.C. 564 = 190, it is often possible to determine, with a fairly high probability, the number of intercalations between two years without being able to decide either the lengths of individual intercalations or their total length; that is, the date is fixed within narrow limits of precision. The accumulated imprecision in dates between a regular year in this period and A.U.C. 564 = 190 is given in the cell for Intercalaris in olive, in the format "D = +N/-M" where +N is the maximum number of days after the given dates that is permitted by the analysis and -M is the maximum number of days before the given dates that is permitted by the analysis.

• For years before the Caesarian reform of A.U.C. 708 = 46.

  • If it is known directly from source evidence that the year contained an intercalary month, rather than by inference from other years, or if it is explicitly stated that that year was a regular then the Intercalaris entry is boxed in red.
    

  • If the source evidence clearly implies an intercalary month, then the Intercalaris entry is lightly boxed.
    
  • If the intercalation was 22 days, the start of Intercalaris is underlined; if 23 days it is not.
    
  • If the length of the intercalation is specifically stated in our sources, the date is given in bolded blue.
    
  • If a date in Februarius is known which is based on a festival (the Quirinalia, Feralia or Terminalia), the Februarius entry is boxed with bold red dashes: ––––––:

• For years after the Caesarian reform of A.U.C. 708 = 46:

  • Starting dates for the seventh month Quintilis are given in blue after the month was renamed Iulius, in A.U.C. 710 = 44.
    

  • Starting dates for the eighth month Sextilis are given in blue after the month was renamed Augustus, in A.U.C. 746 = 8.
    
  • Starting dates for the ninth month September are given in blue during the period the month was renamed Germanicus, in A.U.C. 790-793 = A.D. 37-40.

Nundinal Letters

The rightmost column gives the nundinal letters in the sequence A-H associated with the Roman market day in the corresponding civil year. This is one of the most important tools available for validating a reconstruction of Roman chronology.

The following conventions are used:

• The cells containing nundinals for the market days directly supported by source evidence are highlighted with an orange background.
  

• If a year is intercalary, a pair of nundinal letters is given, representing the letter of the market days before and after intercalation (except under the Julian calendar after A.U.C 746 = 8, where the reconstructed letter assumes that the bissextile day was omitted from the nundinal cycle).
  
• The nundinal letter(s) for years in which the market day fell on Kal. Ian. (i.e. had a nundinal letter of A) are bolded, since (at least after A.U.C. 677 = 77) this was regarded as a sign of ill-omen and generally avoided.

It should be noted that the nundinal letter given here, or the first nundinal letter of a pair, as appropriate, is effectively the complement, modulo 8, of the letter given by most Roman chronologists. The standard convention would represent the nundinal letter of Kal. Ian. if the cycle of letters was uninterrupted, like the modern week. However, the cycle was actually reset at the start of every civil year, and the important datum is not Kal. Ian. but the market day. The standard convention not only does not represent the market day, except by coincidence, but it is also anachronistic. The values shown here reflect actual Roman practice rather than the normal modern convention. The two may be converted as follows:

Roman:           A B C D E F G H
Conventional:  A H G F E D C B

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