Some ancient calendars
The indication of the Julian date of the first month in each calendar is only an approximate guide. All of these calendars varied, some of them very widely, from their supposed starting point in the solar year. For more information about each of the calendars, see the detailed chronological tables that have been compiled by Chris Bennett.
Babylonian (Jewish) calendar
Month 1 : Nisanu (Nisan) ≈ April
Month 2 : Aiaru (Iyyar)
Month 3 : Simanu (Sivan)
Month 4 : Duzu (Tammuz)
Month 5 : Abu (Ab)
Month 6 : Ululu (Elul)
Month 7 : Tashritu (Tishri)
Month 8 : Arasamnu (Marheshvan)
Month 9 : Kislimu (Kislev)
Month 10 : Tebetu (Tebeth)
Month 11 : Shabatu (Shebat)
Month 12 : Addaru (Adar)
These were lunar months. To keep in step with the solar years, intercalary months were added, usually after month 12. During the Hellenistic period, this was done on a regular and predictable basis.
To convert Babylonian dates into Julian dates, see the Babylonian Calendar Converter.
Egyptian calendar
Month 1 : Thoth = first month of akhet season
Month 2 : Phaophi
Month 3 : Hathyr
Month 4 : Choiak (or Choiach)
Month 5 : Tybi = first month of peret season
Month 6 : Mecheir
Month 7 : Phamenoth
Month 8 : Pharmouthi
Month 9 : Pachon = first month of shemu season
Month 10 : Pauni
Month 11 : Epeiph
Month 12 : Mesore
All the months were 30 days long. They were followed by 5 epagomenal days at the end of the year.
During the Hellenistic period, the date of Thoth 1 moved regularly backwards in the Julian calendar, from 12 November in 324 B.C. to 30 August in 30 B.C.
To convert Egyptian dates into Julian dates, see the Date Converter for Ancient Egypt.
Greek (Athenian) calendar
Month 1 : Hecatombaeon ≈ July/August
Month 2 : Metageitnion
Month 3 : Boedromion
Month 4 : Pyanepsion
Month 5 : Maemacterion
Month 6 : Poseideon
Month 7 : Gamelion
Month 8 : Anthesterion
Month 9 : Elaphebolion
Month 10 : Munychion
Month 11 : Thargelion
Month 12 : Scirophorion
These were lunar months. To keep in step with the solar years, intercalary months were added every few years. However, it seems that these did not follow any regular cycle, and therefore it is usually impossible to establish the exact equivalent of an Athenian date in the Julian calendar.
Macedonian calendar
Month 1 : Dius ≈ October
Month 2 : Apellaeus
Month 3 : Audnaeus
Month 4 : Peritius
Month 5 : Dystrus
Month 6 : Xandicus
Month 7 : Artemisius
Month 8 : Daesius
Month 9 : Panemus
Month 10 : Loius
Month 11 : Gorpiaeus
Month 12 : Hyperberetaeus
These were lunar months. To keep in step with the solar years, intercalary months were added every few years, at a time determined by local custom. This calendar was widely used in the Hellenistic period - in Egypt, in Syria, and in Macedonia itself - but unless more information is available (for instance a 'double date'), it is usually difficult to establish the exact equivalent of a Macedonian date in the Julian calendar.
Roman (pre-Julian) calendar
Januarius (29 days)
Februarius (28 days)
Martius (31 days)
Aprilis (29 days)
Maius (31 days)
Junius (29 days)
Quintilis (31 days)
Sextilis (29 days)
September (29 days)
October (31 days)
November (29 days)
December (29 days)
These were fixed-length months, and a 'regular' year was 355 days long. An intercalary month could be added after February to bring the calendar back into line with the solar year. The intercalary months were not inserted in any fixed cycle, but enough other data is available for some years to make it possible establish the equivalent of a Roman republican date in the Julian calendar.
To convert Roman dates into Julian dates, see the Roman Calendar Conversion Table, with Guidance.
Attalus' home page