Danish calendar

In my last post I talked about the Julian and Gregorian calendars. Since then I’ve added the Danish calendar and some danish translations. For the Danish calendar I’ve also added more named days of the years and ran into some challenges or questions which I’ll describe more in this post. If you just want to see the result, feel free to visit the calendar.


Along with introducing the Danish calendar, I’ve introduced danish translations to the calendar application. This work is not complete. Especially for the parts of the application that haven’t been developed yet, I have not translated the placeholders that explain what is to come yet. However, I have laid the ground work, and will expand the translations as new functionality is introduced.

Danish calendar

The Danish calendar that I’ve implemented is mostly just a mix of the Julian and the Gregorian calendars. I use the Julian calendar up until the 18th February of 1700 and then switch to the Gregorian calendar from the 1st of march, similar to how the switch was made in Denmark.

I’ve added some more named (church) days to the Danish calendar. At the time of writing I haven’t added more named days for the Julian and Gregorian calendars. I’m only keeping the Julian and Gregorian calendars in case somebody wants to use the calendar for other countries and know when the switch was for that country.

As mentioned in my earlier post the switch between calendars was different for different countries. And even some of the church days continue to fall differently between countries. Most notably many of the Eastern Orthodox churches adopted the Revised Julian calendar rather than the Gregorian calendar. The dates align until 2800, but most of the churches calculates Easter based on the old Julian calendar, causing Easter and other celebrations relative to Easter to often fall on different weeks.


In Denmark we have had changes to some of the church days. One of the important days, Annunciation (Mariæ bebudelse) has been changed a few times. It was originally observed on the 25th of March, but then changed by Christian V’s Danish Law of 1683 and later by the holiday reform of 1770 according to Wikipedia. In the Danish Law it was changed to fall on the Saturday before Palm Sunday, if Palm Sunday falls on March 25 or earlier. In the holiday reform it was pinned to the 5th Sunday in the Lent.

The Danish Law was officially issued on April 15, 1683. With regards to Annunciation it seems it would be in effect the year after. Similar, the holiday reform is from October 26, 1770 and so with regards to Annunciation would be in affect the year after. That leaves us with the following ways of determining Annunciation:

  • Until 1684: March 25.

  • 1684-1770: March 25 or the Saturday before Palm Sunday if Palm Sunday falls on 25th of march or earlier.

  • From 1771: The 5th Sunday in the Lent.

I’m unsure when the laws where actually in effect, but these years are my best guesses. To try and verify I looked at some of the other calendar sites out there. The ones that are based on R. W. Bauer’s work (e.g. here and here), seem to always use March 25. I’m assuming this is because that is what Bauer did, although I don’t have his book with me at the time of writing. There is another site (DinSlægt.dk), which is incorporating and describing similar changes as above. However, it changes in 1687 rather than 1684. The site seems to have Norwegian roots and I’m guessing this is the reason for making the change in 1687 instead. The Norwegian Law was issued in 1687 and in content was approximately identical to the Danish Law, according to Wikipedia. Whether the Norwegian Law was actually in effect in 1687 may be another matter (according to Wikipedia it went into effect September 29, 1688).


From my small reading on Wikipedia and the small test of other services it is still unclear, when Annunciation was actually observed in Denmark in the different years. Or when the changes were effectuated. I’ve made my best guesses, but if you have more knowledge on the matter I’ll be happy to hear from you, in the comments or by mail to feedback@estorical.com.

Similar if you have other information about how the church recorded the years and the named days. I’ll also be happy to hear from you.

Until next time

Having implemented an initial version of the Danish calendar there are so many things that I want to do next. I should test more thoroughly that it calculates the weekdays and church days correctly. I also want to be able to click a named day in the year and see more information. I also want to implement some of the other features of getting help to search for a specific day, by entering whatever one can gather from the church book and then have the application suggest what it might be from alternative names, known abbreviations and so on. I will have to choose one thing and get started on and I’ll give an update in a couple of weeks.