The Official Calendar of Res Publica Romana

by | Sep 1, 2023 | Uncategorized | 0 comments

The calendar is in many ways at the heart of any Roman community. It controls the actions of the magistrates, it defines the schedule of religio publica, the public part of Roman religion and it also steers the lives or Roman citizens. Roman calendar was and is in many ways similar and in the same time many ways different compared to our modern calendar. It is also worth to note that there is no single correct Roman calendar – each Roman community had its own. In this post we take a look into some aspects of both the Roman calendar as well as spesifically into the official calendar of Res Publica Romana.

The roots of the Roman calendar are very old and during the millenniae it has seen many changes and modifications. One of the most widely known modification was made by C. Julius Caesar, hence the name Julian Calendar. One of the first tasks for anyone trying to create a modern version of the Roman calendar then is to decide which period of historical Roman calendar is to be taken as basis for it.

Also one has to consider that each Roman community, city, town or even village, had its own calendar with own local festivals for own local deities. Some historical Roman calendars have been survived to us and they can be used as basis for reconstruction. We also have information about Roman calendar survived in Roman literature and letters etc. A strong candidate for the official Roman calendar would the calendar followed in the city of Rome, but curiously enough we do not have a single one survived from there. So we must acquiesce that there is no single “official” Roman calendar.

When we set to create our own Roman calendar for the Res Publica Romana we took some survived calendars from the republican period as basis. We set to follow Julian and Augustan modifications into number of months and number of days in each month.


The number of months has been in the Roman calendar the same as in our current modern calendar. The names of the months are also mostly familiar ones to us, so the basic division of Roman calendar is easy for modern person to understand. In the old times Roman months Januarius (January) and Februarius (February) were of annually changing duration declared by the priests. This caused confusion and before time of Caesar it might happen that the calendar was 6 months off from the natural turn of the year, which meant that rains for the crops were prayed from the gods in the middle of Winter rain season. This was the reason why modification was made to turn the Roman calendar to follow the natural solar year. Also the length of the January and February were regulated. As this corresponds well with our modern calendar, we have decided it best to follow this modification.


Romans had a 8 day week, so this is an obvious difference compared to our modern calendar. Romans marked these days by letters from A to H. The special day of each week was market day, not day of rest or weekend, like in our modern calendar. At the beginning of each year the priests declared which day would be a weekly market day. So for example it could be C day or F day this year etc. Romans didn’t have a weekly day off from work, but market day would break the normal cycle and Romans had plenty of religious festivals throughout the year. When we designed the official calendar for the Res Publica Romana we wanted to keep 8 day week and market day tradition because they were so important to the Romans and their sense of time.


One of the most remarkable differences between the ancient Roman and our modern calendar was the concept of types of days. Romans were observant on what type of day was and consequently, what they could do at that type of day. Some days were considered to be unlucky days, some sacred to divinities and some suitable for political or other activities. This division into different types of days controlled Roman public and partly private life, and therefore was so integral part of the life of a Roman community, that we decided to include it into our official calendar of Res Publica Romana. Here are the different types of days, with their explanation:

Dies FASTI (F)
These are dies profesti, normal working days in which the Gods favour human activities. 1. Tribunals may be open and the praetores may fully perform their duties. Petitio actionis and other documents may be accepted. 2. Marriages and private worship may be celebrated. 3. Contiones may be called and celebrated. Citizens may express their will, but any vote conducted will not be binding for the magistrates. 4. Markets may be open, business may be made, contracts may be signed. Private activities may take place normally.

These are identical to dies fasti, but they are reserved for the celebration of public assemblies. 1. If no magistrate calls any of the Comitia on a dies comitialis, it shall be treated as a dies fastus. 2. If a magistrate calls the Comitia, a vote may take place. The result of vote would be binding for the magistrates.

They are dies profesti (working days) that present some restrictions due to their religious character. 1. Tribunals may be open and petitiones actionis and other documents may be accepted. However, the praetores cannot pass a sentence (because they cannot say the words do, dico, addico). 2. Public worship has preference over private worship. It is not recommended to celebrate marriages. 3. Comitia should not be called. Contiones may be called to inform the People, but no voting should take place. The Senate may meet, but affairs concerning cultus and religio should be dealt with before any civil affair in the Senate agenda. 4. Private activities are not favoured. It is not recommended to begin a journey or to sign contracts, or to generally start a new activity. Actions begun on a previous day, however, might be carried on normally. Markets may be open.

These are “cut asunder” days, that prepare the feria of the following day. They are dies profesti (working days) with certain restrictions. They are dies nefasti in the morning (horae I to IIII) before and during the celebration of the sacrifices; but they become dies fasti at noon (horae V to VIII) and nefasti again in the evening (horae VIIII to XII) during and after the offering in the altars of the sacrifices performed in the morning.

A dies nefastus publicus is a dies festus, a holiday for all citizens (not for slaves), because they are reserved for public worship and dedicated to a given god (feriae). All the NP days are feriae publicae pro populo, but not all dies feriati are NP. They have the same characteristics as a dies nefastus, but tribunals are closed (because magistrates have to attend public religious ceremonies). These include fixed holidays (feriae stativae), mobile holidays (feriae conceptivae) decreed by magistrates and irregular holidays (feriae imperativae) decreed by the Senate.

The meaning of this fastus is not yet completely clear. Further research is necessary, and the pontifices will one day issue a new responsum concerning this particular fastus. For the moment being, the pontifices recommend to treat these days as if they were NEFASTI PVBLICI.

Quando Rex Comitiavit Fas (QRCF)
These are fixed days (dies fissi) in the calendar, and they are also dies feriati (religious workship takes place) but dies profesti (working days). They are a dies nefastus from dawn till the Rex Sacrorum appears in the Comitium and performs the purifying rites. From then on it is a dies fastus and the Comitia may be adjourned.

Quando Stercus Delatum Fas (QSDF)
These are fixed days (dies fissi) in the calendar, and they are also dies feriati (religious workship takes place) but dies profesti (working days). They are a dies nefastus from dawn till the vestales finish cleaning the Temple and the House of Vesta and take the garbage out of the sacred grounds through the Porta Stercolaria. Garbage is then swept down the streets and thrown to the Tiber. From that moment onwards, it is a dies fastus.

These are “dark” days on which no sacrifices are properly made. No sacrifices should be offered on public altars. Neither shall the temples celebrate public worship nor hold sacrifices on these days, public Augures may not take auspicia on these days, nor should magistrates hold elections on these days. All religious ceremonies are private but without sacrifices. No one should invoke a God or Goddess by name while indoors, and no celestial God or Goddess should be invoked by name while outdoors. It is not fitting to offer sacrifice to the spirits of the dead on dies atri either, because in such ceremonies it is necessary to call upon Janus and Jove, whom it is not right to call upon on dies atri. Making journeys, starting new projects, or doing anything risky should be avoided. These days, so marked as dies atri, are religiosi and are always considered as dies fastus (F) or dies comitialis (C), never as dies nefastus (N) or dies nefastus publicus (NP). The dies atri include two special subcategories: 1. Dies POSTRIDUANI: These are the days after all the Kalendae, Nonae and Idus of each month. They are, in general terms, dies fasti (F), but they are days of ill-omen for beginning private activities, business or journeys. Public worship is explicitly forbidden. 2. Dies VITIOSI: These are specific dates decreed by the Senate, and considered unlucky days. The only two fixed dies vitiosi are the dies ALIENSIS, on July the 18th, a. d. XVI Kalendae Sextiliae, and August the 2nd, a. d. IV Nonae Sextiliae. Additional dies vitiosi, should they be needed, may be declared by the Senate through passage of a senatusconsultum.

These are days dedicated to the worship of infernal deities and of the dead; worship to celestial deities should not take place, and temples of celestial deities should close their doors. All ceremonies are private and celebrated in domestic shrines by the pater familias. These are always a dies nefastus (N), never a dies fastus (F), dies comitiales (C) or dies nefastus publicus (NP).

Nundinae and nundinal letters
Nundinae were originally market-days, held every eighth day, on which Romans came into the city to trade and do business. On Roman calendars the days were given nundinal letters (A to H) to help people see when the next market-day would be. The markets were held on a different day each year – this year they are held on “D” days. When a market-day falls on a dies comitialis (C), nefastus (N), or endotercisus (EN), it becomes a dies fastus (F).

Kalendae is the first day of each month, Nones the first Moon of the month and Idus the full moon of the month. These form the basis for the Roman numbering of the days of the month. Romans didn’t number the days of the month running from 1 onwards like us, but rather they calculated how many days there are until next Kalendas, nones or idus. So last day of April is the first day before Kalendas of May (Pridie Kalendas Maius, pr.kal.mai.) and May 2nd is the sixth day before the Nones of May (a.d.VI non.mai.) This way of numbering of days is perhaps quite confusing to the modern person to follow, but nevertheless it was the custom of the Romans.

We followed the survived ancient Roman calendars to define the type of day for each day of the year for our official calendar for Res Publica Romana. In conflicting cases we decided to follow older Republican period calendars when possible.


The many religious festivals were very important to Romans and they set the annual rhythm of life. Some festivals were big public spectacles provided by the magistrates for the people of Rome, some of less importance. It was also up to the individual which festivals he choose to feast and how. When deciding about which festivals to include in our official calendar of Res Publica Romana, we tried to make a balanced selection of most important Roman festivals and keep the calendar balanced throughout the year.

How to get your own copy?

taberna_curii_fasti_romani_posters_2017The official calendar of Res Publica Romana is annually published by the consules at the RPR Contio citizen mailing list.

You can also order a printed copy of the calendar through our Cafepress -shop.