The Germanic Lunar Calendar – A Source-Based Lunisolar Calendar

In the Poetic Edda, gods, humans, giants, and dwarves each have their own word for the same thing. For the Moon, the Alvíssmál says, the Álfar say "Ártala," the year-counter. That single word gives away what the Germanic lunar calendar is about: the Moon was the instrument by which our ancestors read off their year, not just a light in the night sky. Even the word "month" still carries this origin today. In every Germanic language it is a direct derivation of "moon."[1]

The Germanic lunar calendar was, for what it was, a lunisolar calendar. Every claim in this text is backed by sources. How humanity worldwide reckoned by the Moon, from Scotland to Japan, is covered by the companion article on the history of lunar calendars worldwide. Here we go into the Germanic special case in detail, and how the Ártala app makes it usable again today.

What is a Germanic lunisolar calendar?

A lunisolar calendar – Andreas E. Zautner calls it the "bound" lunar calendar – links two celestial bodies.[3] The Moon sets the beat: every month is a lunar month. But a pure lunar calendar has a problem: twelve lunar months are about eleven days shorter than a solar year, so the months drift against the seasons over the years. The Germanic calendar solves this by binding the lunar cycle to the solar year: every few years a thirteenth month, a leap month, is inserted. The one fixed solar point the whole system hangs on is the winter solstice; the start of the year, leap years, and festival dates are all derived from it.[5][6] This keeps the calendar permanently in step with sowing, harvest, and the seasons, without giving up the Moon.

Moon, month, night: how the Germanic peoples measured time

A Germanic month does not begin at the astronomical new moon, but on the evening the first thin crescent becomes visible again – the Ny, the "new kindling."[3] The full moon, Fullid, forms the middle of the month and carried the great feasts; at month's end stand the three lightless nights of the dark moon, Nið, which still count toward the old month, not the new one.

Time was counted in nights, not days, altogether. Tacitus reports as early as around 98 AD in the Germania that the Germanic peoples set their assemblies by new or full moon and reckoned by nights rather than by days: "nox ducere diem videtur," the night seems to lead the day.[2] This way of counting has not vanished: anyone who speaks of "a fortnight" (literally fourteen nights) or of the Twelve Nights around the winter solstice is still using this old measure. And "month" is, linguistically speaking, simply a "moon": proto-Germanic mēnōþ ("month") is a direct derivation of mēnō ("moon"), with the same traces in Old English mōnaþ, Old Norse mánaðr, and Gothic mēnōþs.[1]

Months and month names in the Germanic calendar

Twelve lunar months make up the regular year; in leap years a thirteenth is added. The names Ártala uses follow the Anglo-Saxon month names that Bede recorded around 725 in De temporum ratione (chapter "De mensibus Anglorum"), and their Old Norse counterparts.[4] The year begins with the Late Yule Month, whose full moon carries Midwinter (Yule), and ends with the Early Yule Month, into which the winter solstice falls. The familiar German series from Hartung to Julmond is deliberately not adopted, since it follows the Julian division into twelve and stems in large part only from the 19th century; which of those names is how old is shown in the portraits of the German month names.

(Month names and mapping after Bede[4] and Zautner[3].)

Leap rules and the role of the winter solstice

When a year begins is decided by the Yule-Moon rule: the first new-moon crescent after the observed winter solstice opens the Late Yule Month, the first month of the year; its full moon is Yule.[5] In about a third of years the crescent ignites before the solstice; in that case it is the Early Yule Month instead, and Yule does not fall until the next full moon.

Whether a year becomes a leap year is revealed by an equally simple observation: if the new moon falls within the twelve nights after the winter solstice, the following year inserts a leap month.[6] The reason lies in the arithmetic – the solar and lunar years differ by around eleven days, roughly the span of the twelve nights. A new moon in this window signals that the correction is due. This "farmer's rule" is remarkably accurate; independent reconstructions (Nordberg 2006, Stanfield 2019) arrive at mathematically equivalent formulations.[6]

The leap month itself sits in the middle of summer, as the Third Litha-Month between the seventh and eighth months, and not in the dark of winter.[7] There is an astronomical reason for this: the summer half of the year, at around 186 days, is somewhat longer than the winter half at around 179 days. So over the years, the extra 13th lunar month falls more often within summer, and the summer insertion keeps the midsummer date cleanly in the seventh month. Bede attests exactly this "three-Litha year" (þrilíða).[4][7]

The eight-year cycle (octaeteris) and the Aun rule

Over the years this adds up to a larger pattern. Eight solar years correspond almost exactly to 99 lunar months (a difference of only 1.6 days), and exactly three leap years fall within eight years.[8] Antiquity already knew this eight-year cycle as the octaeteris. Every eight years, therefore, an especially large midwinter feast, nine nights long, occurs. The rhythm is attested more than once: Thietmar of Merseburg reports it around 1015 from Danish Lejre, Adam of Bremen around 1075 from Swedish Old Uppsala, both as a feast held "every nine years," which reflects inclusive counting.[10] An old mnemonic even records the yearly shift of full-moon dates: the Moon jumps "twelve and twenty."[9]

The dedicated article on the octaeteris covers this in full: why the cycle grew out of the needs of a sacrificial calendar, how the Aun rule works as a memory aid, and how it relates to the more accurate Metonic cycle.

The festivals of the yearly cycle

This is where the calendar becomes most tangible in practice, because most festivals do not hang on a fixed date but on the interplay of Moon and season. Three full moons structure the year: the full moon of the Late Yule Month is Yule, the midwinter feast, whose name lives on in the Nordic "Yule" and whose customs have flowed into our Christmas. Half a year apart, the full moon of the Easter-Month marks Sumarmál, the start of summer, and the full moon of the Winter-Month marks the Winter Nights (vetrnætr), the start of the winter half-year.[11] Summer and winter, the two great seasons of the Germanic division of the year, are each opened by a full moon.

In between lies a series of Blóts, the Germanic sacrificial feasts documented in the kings' sagas of the Heimskringla and by medieval authors; their recurring blessing was til árs ok friðar – "for a good year and peace."[12] In deep winter stands the Þorrablót, in late winter the Góiblót and the mid-Swedish Disting – with scholarship carefully distinguishing between the Disting market-thing and the often-confused Dísablót, the autumn sacrifice to the female Dísir.[13] Closely related but not the same is the Álfablót: also a private autumn household sacrifice, here to the Álfar, of which the sources emphasize that strangers were not admitted to the house.[14] Spread across the year, the great popular assemblies, the Things, gather around this rhythm – from the spring thing through the multi-day Althing to the autumn Leiðmót (autumn thing).

Rauhnächte: the difference days between the lunar and solar year

The time around the winter solstice is especially dense – and it has a neat calendrical logic. Twelve lunar months are about eleven to twelve days shorter than the solar year, and exactly these "surplus" days between the end of the lunar year and the start of the next are, according to a widespread interpretation, the Rauhnächte, the Twelve Nights "between the years."[16] This is why the Rauhnächte are not an arbitrary custom: they are the visible seam of a lunisolar system.

They are opened by Mother Night (Modranecht), which Bede attests for the night before December 25.[15] Linguistically correct, this means "night of the mothers" – referring to the Dísir, female protective powers of the household; the popular reading as "mother of all nights" is a later misinterpretation.[15] This also shows the standard Ártala holds itself to: where an interpretation is well documented, it is presented as such; where a connection is plausible but not certain (like the exact derivation of the Rauhnächte), that is stated as such, rather than declared a certainty.

The sources: Tacitus, Bede, Grágás, Adam of Bremen

None of this knowledge is invented; it is reconstructed through source criticism. The authoritative work is Andreas E. Zautner's Der gebundene Mondkalender der Germanen (Edition Roter Drache) and the sources cited within it.[3] A separately built source and knowledge database regularly supplements and confirms the findings. Crucial here, and rightly taken seriously in the pagan community, is a distinction that often blurs in "Germanic" circles: Zautner's book is a reconstruction, i.e. secondary literature. The actual evidence is the ancient, medieval, and early-modern texts he evaluates. Ártala maintains this separation between finding and interpretation, and honestly says "we don't know that" where the sources are silent. This separation is what distinguishes a source-based tool from an esoteric toy.

The key witnesses are quickly named. Tacitus provides, in the Germania (c. 98 AD), the oldest evidence for lunar and nightly counting.[2] Bede transmits around 725 the Anglo-Saxon month names, Mother Night, and the thirteen-month structure with the leap year.[4] The Old Norse legal texts – above all the Icelandic Grágás – show how deeply timekeeping was anchored in law: they regulate the counting of summer and winter in weeks and the dates of the Things.[18] Adam of Bremen describes around 1075 the Uppsala sacrifice on its eight-year rhythm.[10] Add to this the Poetic Edda (from which the word "Ártala" comes), the kings' sagas of the Heimskringla, and, as a younger, Christianized relative, the Norwegian Primstav, whose oldest surviving example dates from 1457.[17]

Using the Germanic lunar calendar today: the Ártala app

This source work has become a tool. It started quite analog: since 2016, after reading Zautner's book, the thought of making this calendar usable again would not let go; the result was first a printed wall calendar (2017 through the "12021" H.E. edition), from 2020 with the month illustrations by Nils Broß. The abbreviation H.E. stands for the Holocene Era ("Human Era") – a proposal by geologist Cesare Emiliani from 1993: add 10,000 years to the Gregorian year and place the zero point at the start of the Holocene, i.e. at the beginnings of settled life and agriculture rather than a religious date. This avoids negative year numbers and the missing "year zero" and represents the depth of human history more honestly; Ártala displays the H.E. count alongside the familiar date.[19] Today Ártala is an app that takes over exactly the calculation and research work that always made the lunar calendar unwieldy in daily use: it calculates moon phases astronomically correctly, even offline (thanks to Jean Meeus's astronomical formulas as a "calendar engine" running directly on the device), shows the festival calendar with the inserted leap month, and reminds you of festival dates. Every festival has an entry in the Blót lexicon with a source citation – visibly separated into finding, reconstruction, and assumption, constantly expanded and regularly quality-checked against newly incorporated sources.

The project is accompanied by its subject-matter mentor Andreas E. Zautner, the atmospheric illustrations come from Nils Broß, and since 2026 the Eldaring e. V. has co-supported the development. Eldaring members therefore get full access at a discount. More on the background and origin of the project is in about the developer of Ártala. The app itself, with which you can look up which lunar week you're currently living in, or which lunar month you were actually born in, can be found for web, Android, and iOS on the Ártala home page. This is what makes the Germanic lunar calendar livable again.