The Viking Calendar

Posted by Raid Commander on

The Viking Calendar

This Post could just as easily have been called The Icelandic Calendar or even The Scandinavian Calendar.

Indeed, even if I admit not to have checked too much, I think it corresponds to the old calendar of the Scandinavian countries (Sweden, Norway, Denmark and Iceland).

But, let's face it, the Viking calendar has a catchy adventure feel. In any case, it has the advantage of situating the period we are going to study.

A little bit of Viking history :

The origin of the word Viking is not very clear. The most likely etymology is that which brings the term of the old Vik Nordic Vik, which means bay, closer to the term. The Vikingr would therefore have been a pirate who frequented the bays.

The Viking period, according to historians, dates from 793, the date of the Danish sacking of Lindisfarne Abbey in England, to 1050.
Some even put the end of this period in 1066 with the death of Harald Hardada at the Battle of Hastings won by William the Bastard (or The Conqueror) over Harnold of Wessex. But it would actually be a Normandy-Norman event.

If we are still at a vision of a barbaric and uncultured people, it is better for us to make this small visit.

Our aim on this page is, more modestly, to learn about the context in which the Icelandic calendar has grown.

And if we assume that astronomical knowledge is essential to navigate or practice cabotage, we will be served. And since a calendar cannot be built without astronomical knowledge, we will ask ourselves questions.

In the meantime, let's start our bit of history and divide the Viking history into major periods.

  • The first (800-850) is characterized by the first predatory expeditions of the Scandinavian beginners. They act by helping: disembark, steal, leave. They sail on boats that are knörr or skeid. In short, everything but drakkar.
  • 850-900 saw them organized into bands and made the headquarters of the great cities (Paris, London...).
  • 900-980 is the period when they began to settle permanently in some countries and colonized others.
  • 980-1050 is the time of a more military and warlike organization of expeditions. The Viking phenomenon will end following the Christianization of the Nordic countries with strong kings who will align themselves with southern customs.

Viking "expeditions" during these periods will follow three distinct routes:

1) The northern route (nordrvegr) with cabotage along the Baltic coasts including Denmark and Sweden as well as equipment across the Atlantic.

2) The western route (vestrvegr) from Denmark and Norway to the North Atlantic Islands, Iceland (871-930), Greenland, North America and cabotage on the coasts of Holland, Belgium, France, Spain, Italy and Greece.

3) The eastern road (austrvegr) from Finland to the Russian Lakes and the Caspian Sea.

The Viking Calendar

If we want to better understand the structure of the Icelandic calendar, we need to forget our modern notions of months and years and put others in our minds:

- The first is related to the latitude of the countries in which the Viking calendar was practiced. This latitude means that, by schematizing to the extreme, the Sun does not set for six months and does not rise for another six months.

- The second is that the populations of the Viking era were very attached to the number 7 (religious phenomenon?) and therefore to the 7-day week.

  • First division of time

From this point on, we better understand that their first division of time is the "season" called Misseri. Each weaver represented approximately half of our year. One was called sumar (summer) and the other vetr (winter). But make no mistake, these misseri are less seasons in the climatic sense of the word than a word to name a period of time.

In the poetic Edda (or ancient Edda, which gathers poems composed between the 7th and 14th centuries) we find a few lines on this division of "the year" into two periods.

"Vafthruthnir spoke:

... Vindsval is the father of winter
and Svosuth begat the summer..." Very free translation on my part.

Let us note in passing, for the record, that in the same Edda, we learn that Mundilferi is the father of the Moon (Mani) and the Sun (Sol). But contrary to what we may think, it is the Moon the son and the Sun the daughter.

  • Second division of time

As we have seen above, the second division of time will naturally be the week. Each day had a name and we can draw up a table of the days of the week.

Viking Day
Sunday Sunnudagr Sun Day
Monday Mánadagr Moon Day
Tuesday Týsdagr Tyre Day
To get to know these Gods and Goddesses better, visit the blog section Nordic Gods
Wednesday Óðinsdagr Day of Odin
Thursday Þórsdagr Day of Thorr
Friday Frjádagr Freya Day
Saturday laugardagr Laundry day  


  • Cohabitation of the two divisions

For want of anything better, we will call the group made up of the two summer-winter misseri the year.

This year had 364 days grouped in 52 weeks.
26 of these weeks constituted the summer misseri and the other 26 the winter misseri.
At least for regular years because we suspect that there were longer years since 364 days are far from 365.25 days, the duration of a tropical year.

The months

Yes, it must be said that the months also existed in the Icelandic calendar. And here, two schools propose different hypotheses.

The first hypothesis is that the Icelandic month was identical to the month we know, i.e. a very precise period of the year with a precise number of days. The year would have been 12 months of 30 days with an additional 4 days outside the month, two in summer and two in winter. Here we find the Egyptian calendar with its 12 months of 30 days. The difference is in the epagomenal days which would be 4 in the Icelandic calendar (obligatory weeks) against 5 in the Egyptian calendar.

The second hypothesis is that the Icelandic month has little to do with our modern notion and that it was rather a period without large fixed limits. A little like we sometimes say "during the summer holidays". We understand what we want to say without limiting the period.

But why bother with this notion of months? The explanation would be that a lunar calendar was imported, perhaps brought by the Vikings, to Iceland. Its inhabitants would have used it when they could, that is, when the Moon was observable, especially in winter. For the rest of the year, they would have used the week. This phenomenon would have lasted until the week alone replaced the week/month couple. Of course, the months came back in force when the Julian calendar was adopted.

Let's draw the table of the months of the year without specifying too much the start dates but just the period covered in the Gregorian calendar.

Période couverte
Période couverte
Décembre-Janvier Sólmánuður
Janvier-Février Heyannir
Février-Mars Tvímánuður
Mars-Avril Haustmánuður
Avril-Mai Gormánuður
Skerpla Mai-Juin Ýlir Novembre-Décembre


Additional weeks

As we have seen in our bit of history, the Vikings were advanced enough in astronomical knowledge to be satisfied with a year of 364 days. It seems that, at first, they were content to add from time to time a day or two to the year to avoid a too important drift in the calendar. But this solution was not satisfactory, on the one hand because it did not allow for a time-bound calendar and on the other hand because the added days were necessarily outside any week.

The solution came from the Althing, a plenary assembly that met annually in the open air at the Thingvellir site ("assembly plains") in the southwest of the island and was created in 930.

Ari Thorgilsson "the wise" in his "history of Iceland" (Islendingabók) written around 1120 tells us about the reform that was implemented by the Althing in 955:
The thingvellir site where the first "parliament" in Europe, the Althing, was based outdoors.
It is also on this highly symbolic site that Iceland's independence was proclaimed on June 17, 1944.

"... the wisest men in the country had counted 364 days or 52 weeks in two semesters - while they observed, due to the movement of the Sun, that summer moves towards spring...

There was a man called Thorsteinn the Black, a very wise man. When they came to the Althing, he looked for a cure that they have to add a week to every seventh summer and try to see how it would work...

In a correct count, there are 365 days in a year if it is not a leap year that has one more. But, in our countdown, 364 days ago. But when in our count one week is added every 7 years, 7 years are of the same length in both accounts. But if there are two leap years in between that need to be increased, you must increase the sixth.".

To be clearer and to summarize, Thorsteinn the Black proposed to add a week (called Sumarauki) to the summer misseri every 7 years. This method, different from the leap years of the Julian calendar, had the great advantage of respecting the notion of week.

In the second part of his text (in red), Ari Thorgilsson explains the changes made when Iceland switched to the Julian calendar around the year 1000: if there are two leap years (Julian) between the years to be increased by one week (Icelandic calendar), then the complementary week is inserted after the sixth summer instead of the seventh.

The first rule gives us an average year of (7 X 364) + 7 = 2555/7 = 365 days.
The second rule, which is not very simple to interpret, tends to bring the average length of the year closer to that of the tropical year.

But why, quite simply, was not a week interspersed every six years? This would give us an average year of
(6 X 364) + 7 = 2191/6 = 365,17. And then apply the second rule?

This is the question that Þorsteinn Vilhjálmsson asked himself in an article by Archaeoastronomy in 1991. And he wondered whether it was not necessary to take the meaning "in seven years' time" as it was done at the time, i.e. by counting the year in which the countdown began for year 1 of this countdown. A little like we still say "in eight days" to say "in a week", that is to say... in seven days. The debate is open.

Nevertheless, it remains true that during a 28-year cycle, 5 full years of 371 days were added.

In Grágás (a collection of laws and customs from the 13th century that incorporates the previous codes) there is an application rule that the first day of sumar (summer misseri) always starts on a Thursday between 9 and 15 April. As for vetr (winter misseri), it starts on a Saturday between 11 and 18 October. If these rules are not applicable, one adds one week.

Beginning of the year and beginning of the period.

- What was the period of the old Icelandic calendar? That is to say, the Gregorian (or Julian) date which corresponds to the first day of the first year of the Icelandic calendar.

The answer is simple: we know absolutely nothing about it. Some propose the summer solstice of 955 as 01/01/0001. Why not? Why not?

- What was the first day of the year? There are many answers: Some people like the winter solstice while others say it was the summer solstice. The question remains.

It should be noted that the Julian calendar was gradually adopted from the year 1000 onwards and that the transition to the Gregorian calendar was made in
1,700 in Iceland.


We cannot leave the Scandinavian calendars without mentioning the primstav, this calendar engraved on a square section stick or on a double-sided ruler.


The first known examples date back to about 1200 and therefore after the Viking era. They will be in use until about 1700.

Primstav, Rimstock, Runstaf according to the countries (Clogs in England), these calendars were all built according to the same model.

Each side represented a season (4 faces for those built according to the Julian calendar, 2 faces for those designed in the "classic" mode), the bottom of each side was engraved in weeks, the days being above.

They were engraved with symbolic motifs that were certainly as well known as the traffic signs are to us. They thus made it possible to locate oneself in time, in the season and in the year.

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