Talk:International Fixed Calendar

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I see that Simon J Kissane created this article and Janet Davis wikified it. Simon, would you mind citing the origin for the proposal?

This article smelled a little partisan to me, so I spent a few minutes doing some research. I found, started by Canadian Miklós Lente. He offers four different proposals for calendar reform. None of them refer to "Sol," though. It sounds like Yet Another Idealistic Pipedream – more like Esperanto than the metric system (please pardon my bias – after all, I'm restricting it to this /Talk page :-). Still, in the spirit of neutral point of view I merely seek the source of the idea so that all readers can judge its value with full knowledge of its history.

<>< Tim Chambers

I agree with your evaluation in re: pipedreams, Tim, but the United Nations briefly considered it - not terribly seriously, I think. The French Revolution and the Soviet Union each tried 'reformed' weeks. The Soviets had a 10-day week. It didn't take. The combination of Christianity AND the 'workers' thinking they had fewer days off stopped it. As in all things calendrical I keep wishing I could find my copy of Eviatar Zerubavel's The Seven Day Week, which is incredibly informative as well as a good read. --MichaelTinkler

I read it somewhere, I'm sorry I can't recall where... when the United Nations considered calendar reform in the 1950s it and the World calendar were the two main proposals. Now I look at it a bit more, maybe I have the name of the thing wrong... I'm sure I've read it called the "Perpetual Calendar" somewhere, but all I can find is a reference to the "International Fixed Calendar" or the "Cotsworth calendar" or the "Eastman plan"... the thing obviously had a lot of names. Okay, have a look at this website: -- Simon J Kissane

I recall reading about this calendar in the Encyclopedia Britannia when I was at primary school c.1980. My recollection was that it was there called something like 'World International calendar'. The article named the extra month 'Sol' (not 'Midi').

Incidentally the reason I read about it was that I and my brother had independently invented this calendar (aged about 12), almost identical in detail, and subsequently discovered it in the encyclopedia. By strange coincidence we had even also (jokingly) proposed the name 'Sol' for the extra month (!) but decided to opt instead for the more poetic 'Midsummer', which incidentally I see now is also like a conflation of 'Midi' and 'Sol'.

The only difference between our calendar and this one was that we had the leap day at the end of the year, on the grounds that (i) it wouldn't disrupt the week pattern mid-year (and hence disrupt e.g. the mapping from day count from the start of the year onto named dates), and (ii) people would generally be on holiday on New Year's Eve and so the fact that it was an irregular date would be less disruptive to business and the like. Ben Finn 17:48, 30 Apr 2005 (UTC)

I've not heard of the "Perpetual Calendar" as a specific calendar before. The disciption[sic] is almost identical to the "Cotworth and Eastman Calendar". The only difference is that the leap day occurs in the extra month Sol rather than at the end of the year. See the above mentioned web page for more details. Karl Palmen

I've mostly seen this called the "Universal calendar" or the "Cotsworth calendar" (Moses Cotsworth was one of its inventors). It is also essentially the same as the "Positivist calender" of Auguste Comte, except that the latter invented new month- and day-names.

Ben Finn,

That's an interesting story of yours. It is an interesting coincidence. I also agree that the extra day would be better at the end of the year however "Midsummer" would not exactly make sense south of the equator. My idea would be to put the extra month at the end of the year instead of the middle and call it "Yule". Jimp 7Sep05

Coptic calendar and Ethiopian calendar have also 13 months. --Hello World! 03:01, 5 December 2005 (UTC)

But they are far from being equal in length. The 13th month is only 5 or 6 days compared with 30 days for the other months.

In the international fixed calendar, I expect that the extra month was placed in the middle of the year to minimise the displacement of the other 12 months from their Gregorian namesakes.

Karl 4 December 2005

converter program and other stuff[edit]

I independently invented a calendar that was the same as this, but named the 13th month different and placed it one month after the International Fixed Calendar's (IFC) extra month. I made Java code to convert a Gregorian date to the International Fixed Calendar. Should I post the source code on a subpage of my user page and link to it, or posted here in the same manner as that at Doomsday algorithm, or what?

Hope some one answers this. Lee S. Svoboda 22:21, 21 December 2005 (UTC)

Why Sol?[edit]

The name Sol for the thirteenth month sounds rather unsuitable for month name system, based on the Latin names (January, February, etc.). Wouldn't it be more logical to follow the Latin names, use 'Undecimber' and place it after December? And let languages that does not use the Latin system, invent their own name for the thirteenth month. —Preceding unsigned comment added by (talk) 14:44, 21 September 2007 (UTC)

I think that sol means the sun.

I guess that their is no point in having a monday-sunday naming system since the days of each month always stay the same right?--judas (talk) 12:49, 21 February 2009 (UTC)

I agree with you that the extra month should be put after december and kept with the current naming scheme. It makes more sense that way.(Drumz0rz (talk) 13:11, 4 August 2010 (UTC))
This talk page for the International Fixed Calendar article is for discussions on how to improve the article, not on how to improve the calendar. Thanks. --Macrakis (talk) 13:59, 4 August 2010 (UTC)
Besides, putting the extra month in the middle means that the similarly named months in this calendar still roughly correspond with the months in the Gregorian calendar. Otherwise the difference would keep increasing with each subsequent month, but with the extra month in the middle the difference is minimized. (talk) 11:10, 1 March 2012 (UTC)

Months are already out of sync considering some were numbered / named based on a spring new year. Adding a month in the middle named sol makes sense as it is a solstice. Does summer or winter make a difference? I'd say yes and no.... They both are solstices, but putting it in the northern summer makes sense because the addition there keeps the months closest to the current months. June and July are each only pushed off by about two weeks. Adding it to December puts December off by a full 28 days. — Preceding unsigned comment added by Pmheart6 (talkcontribs) 23:11, 17 June 2019 (UTC)

13 month calendar[edit]

The information on this page about the 13 month calendar is not correct because the dates of the beginning and end are not accurate. The calendar actually starts on July 26 and ends on July 24 and the out of time day is July 25 of each year.—Preceding unsigned comment added by (talkcontribs)

Note: I transferred this comment from the article. Mindmatrix 18:58, 23 April 2009 (UTC)

Sol Calendar?[edit]

While this could be placed in the general list of calendars, I put it here because its a derivative of the IFC

First, to why Sol.... I don't have access to the Royal Society of Canada transcripts or any other article scraps on Cotsworth or Eastman, but the with the placement of the month overlaying the summer solstice, did he ever mention solstice? The summer solstice would be on the 3rd day.

Second, notable other calendars (on this page) should list the Sol calendar. That may mean it would also need to be added to the wiki as a calendar.

This listing is an important link for this page not just because it is a derivative, but because it does address several of the CON's i.e. the religious dates. Making 7 days a week i.e. added days are part of a week, and leap days would not affect the second half of the year.

--While less "business" due to not being perpetual, it is possibly more acceptable to the "people" side and thus a viable option for adoption and listing. — Preceding unsigned comment added by Pmheart6 (talkcontribs) 13:45, 21 August 2013 (UTC)

I still see no sol calendar has been added. Sol is also special because unlike the 4 international fixed versions, it keeps days of week in line with the Gregorian calendar. Yes, it's not used like the Eastman /international fixed was, but one of the biggest "cons" days of week that do not line up, is fixed perhaps helping it become adoptable. The opposite happened with the IF/Eastman calendar.

For note, the sol calendar was created by Jim Eikner of Austin, Texas and is a direct descendant of the international fixed calendar. — Preceding unsigned comment added by Pmheart6 (talkcontribs) 23:17, 17 June 2019 (UTC)


This entry cannot be correct. There are phrases like "[...]January 1 in the Cotsworth calendar always falls on Gregorian January 1" as well as "Each month begins on a Sunday, and ends on a Saturday; consequently, every year begins on Sunday". Those two sentences are mutually exclusive. SilentGuy (talk) 07:22, 12 March 2014 (UTC)

It is the Sunday that differs. Sunday in the Cotsworth calendar does not usually coincide with Sunday in the Gregorian calendar. Karl (talk) 13:29, 12 March 2014 (UTC)
Is this true though for all variants: IFC, Cotsworth, Eastman, ...? If I remember correctly Eastman stayed in synchronization with the established week cycle. Either way, the prose should be improved to make this more clear. — Christoph Päper 19:45, 3 June 2018 (UTC)

Year Zero[edit]

Is there a year zero in this calendar?

Does it start from "year 0" or "year 1"?-- (talk) 13:46, 23 October 2016 (UTC)

I believe it uses exactly the same years as the Gregorian calendar. Karl (talk) 11:42, 24 October 2016 (UTC)

Disadvantages, first day of the week[edit]

If this calendar was to be used internationally, the whole world must then agree on which day is the first day of the week. The Gergorian calendar doesn't define which day is the first of the week, so different nations has agreed on different first day of the week, such as Sunday in the Americas, Monday in Europe, Saturday in the Middle East. So the disadvantage with the International Fixed Calendar is that most people will have to use a different first day of the week, or that the week starts with their preferred weekday which would make the weekdays not match up between the nations. – I couldn't find this listed on the article; but this is a significant issue. §Numbered days of the weekLiggliluff (talk) 01:24, 12 November 2018 (UTC)

That's true in principle. However, the closest to an international agreement there is, would be an ISO standard and there is one, ISO 8601, which unambiguously and uniformly specifies Monday as the first and Sunday as the last day of a calendar week. — Christoph Päper 12:36, 29 November 2018 (UTC)


I've made an image and would like to see it on the article. However I'm not a regular wikipedia editor and thus don't know if it's appropriate. So I'll leave it to you to decide. Here's the file: — Preceding unsigned comment added by (talk) 08:45, 28 November 2018 (UTC)

Disadvantage? Food expiry date[edit]

"Expiration dates on food items will have to be converted to the new calendar, and checking the dates to make sure the food is fresh could become harder and more confusing as a result, in the first couple years after the switch."

This is actually not an issue. You decide in advance that "in year 2034, this new calendar will be used from 1 January", because that year starts with a Sunday and the transition will be seamless. All food produced that will have an expiration date in 2034 or later will take the new calendar into account, and before 2034 will take the Georgian calendar into account. This is a non-issue; unless you have food right now that has an expiration date past 2034. Liggliluff (talk) 16:41, 7 August 2020 (UTC)