A Proposed Replacement for Our Messy Calendar

A Proposed Replacement for Our Messy Calendar

In 46 BC, Roman dictator Julius Caesar proposed the idea of the Julian Calendar, a new calendar standard to build on top of the previously existing Roman Calendar, which had 10 months of 30 to 31 days and had been the standard in Rome for many years. Caesar’s proposal for a new calendar looked very much like the calendar we currently use, the Gregorian Calendar, with 12 months of between 29 and 31 days and the inclusion of 366-day leap years every 4 years. Caesar’s influence brought this standard around the world, allowing it to remain in popular use for over 1600 years. Only in AD 1582 did Pope Gregory XIII propose the Gregorian Calendar, a seemingly minor modification to the existing Julian Calendar. The only difference between the two was a small change in how leap years worked— instead of just having one every 4 years, one would occur every 4 years under the condition that the year was either indivisible by 100 or divisible by 400. This brought the average year length down from 365.25 days to 365.2425, a small gap that has only created 13 days of separation between the two calendars at the time of writing, even after the 400 some-odd years that have passed since the adoption of the Gregorian Calendar.

However, as you may have noticed before, the Gregorian calendar is not very friendly. For starters, all of the months have different amounts of days. 7 of them have 31, 4 of them have 30, and one of them has 28— unless it doesn’t— in which case, it has 29. The months with 31 days are not evenly spaced apart. For the most part, they are every other month, but July and August sit right next to each other, and both of them have 31 days. Leap years occur every 4 years unless the year is divisible by 100… unless the year is divisible by 400. Sometimes, it can be a bit of a pain to remember all the rules that the calendar follows.

silver iMac on brown wooden desk

Why is the Gregorian calendar so complicated?

Nonetheless, the Gregorian calendar isn’t like this without reason. Periods of time like days and years are based on the celestial units in our solar system. The Sun and Moon, both of which have existed for billions of years before human civilization formed, have awkward rotational periods when used with our man-made time units. You may know a day as being 24 hours, but it’s not exactly that long― the earth rotates 360 degrees once every 23 hours and 56 minutes, approximately. Because of this, a year, known usually as 365 days long, is really 365.24219 days long. This period of length is called a tropical year, conforming exactly to how the Earth rotates around the Sun. This inconsistency is precisely why the 4-100-400 rule in the Gregorian calendar exists.

Months, however, have an even more complicated history than this. In ancient Rome, a month was controlled by the cycle of the Moon. To move through all of its phases, the Moon takes approximately 29 days and 13 hours, which, of course, doesn’t line up equally with the Sun’s rotation. Because of this, the months in the Roman calendar were all of different lengths― 30 or 31 days. However, since this calendar only consisted of 10 months (like the ancient Greeks’), it only ended up being 304 days long in total. The other 61-ish days that were lost were unaccounted for, and all calendar-related activities were paused during that time (it was winter, anyway). As mentioned before, this was later reformed by Julius Caesar to create the Julian calendar, which had 12 months of either 28, 29, 30, or 31 days and added the inclusion of leap years. While this did account for all of the days in a year, the amount of days per month was even less consistent by month.

But since the Gregorian calendar is the calendar system that is and has been used in the majority of the world for a very long time, it is not at all practical to make the world adopt a new calendar system, even if the change is very slight.

Why don’t we just change how long seconds are?

One possible “solution” is just to change the length of a second to very, very, very slightly longer than what they are now to accomodate for the “extra” quarter of a day that is present in the tropical calendar but not in the Gregorian calendar. If this had been proposed some hundred years ago, it could be a reasonable solution, since nothing in those days really depended on that amount of time precision. However, with the introduction of advancements in technology creating mechanical timekeeping devices in the 14th century and— more recently— computers and other devices that run on super precise internal clocks, this solution becomes less and less practical. Things like the stock market depend highly on how time is kept digitally; any abnormal shift in time would be detrimental if not implemented correctly— not to mention the entire process of getting the length of the second changed and having its new length be published as a computational standard, relying on world agreement.

As we have seen, this rules out the possibility of changing the length of any previously existing time units. However, could we just invent a new time unit… right? It wouldn’t have any conflict with any other time units since it would have just been created, and since we know pretty accurately the length of a year, we could tune it so it’s an even divisor into the length of a year, removing all the unnecessarily complicated stuff like leap year rules.

The problem here, again, is adoption. Seconds, minutes, hours, days, et cetera, have been around as a concept for a very long time. People are not willing to change to a new time system, as we have been accustomed to having 24 hours in a day and however many days in a month for as long as we’ve been alive. This difficulty of adoption is exacerbated by the immense reliance we place on computers and the services that they provide. Changing the minds of people in the world is a very difficult task, but adding computers to that task makes it immensely harder. Code for every application and web service and operating system involving time (which is to say, a lot of them) will need to be changed to adopt to the new system.

A proposed solution: the 13-month calendar

white ipad on brown wooden table

This is where the International Fixed Calendar (IFC), or Cotsworth Calendar, comes into play. First designed in 1902 by Moses Cotsworth (although having existed as an idea prior to 1902), the IFC is a proposed alternative to the rough Gregorian Calendar that is widely used today. Essentially, the calendar split the 365 days of the year into 13 months of 28 days, plus one day at the end (dubbed Year Day; since the following day would be a Sunday, this day was set to be a Sunday as well, thus appropriating the name Double Sunday by Cotsworth). The additional month would be called Sol and be placed between June and July.

Since the Cotsworth calendar still consists of 365 days, leap years still exist (leap days are on June 29th instead of February 29th in the Gregorian) and the 4-100-400 rule still applies. While this keeps calculations beyond a year complicated, it also means that there is no new system, so there are is no addition of new time units or changing of old ones. The only thing that the Cotsworth calendar does, in fact, is shift around the days in terms of months. While this does take adjusting, it was created in favor of organizing time better than the Gregorian calendar currently does.

The League of Nations, in 1923, actually selected the Cotsworth calendar as the best calendar proposal that was offered, spawning the International Fixed Calendar League. The Costworth did actually get publicity and was used by companies such as Kodak for a while. However, it eventually was rejected by the League of Nations in 1937, ending the campaign that the International Fixed Calendar League had started. Since then, things have sort of slowed to a crawl, with Kodak stopping use of the IFC in 1989. Besides, adapting to a new calendar system in this age would be nearly impossible.


The Cotsworth calendar was originally proposed as being a more “rational” calendar system than the Gregorian, which has already been explained to be rough. With 13 months of 4 weeks of 7 days, the Cotsworth is much more consistent and easy to remember than the Gregorian. Every month starts on Sunday the first and ends on Saturday the twenty-eighth; additionally, with this, any particular day of the month will always fall on the same day of week, making it very easy to remember— unlike the constantly shifting day-of-week that the Gregorian presents. Because of this, calendars will be able to be reused year to year, programming with dates will become significantly easier, and project management that usually spans over weeks and months may become simpler.

Also, holidays that traditionally fall on the same weekday every year (e.g. Thanksgiving) will also have a fixed day of the year in addition to weekday. Likewise, holidays that traditionally fall on the same day every year (e.g. Veterans Day) will fall on the same weekday every year. Both of these make the days on which holidays fall on static between years, making it easy to compare and predict them.

On the business side of things, stuff is improved as well. With the Gregorian calendar— since not all of the months have the same days— each fiscal quarter is a different amount of days. Q1 is 90 days long (91 if it’s a leap year); Q2 has 91 days; Q3 has 92 days; and Q4 has 92 days. These seemingly small inconsistencies can have a big impact on how money and other assets are calculated, among other things. However, in the Cotsworth calendar, since each month has 4 weeks, every quarter is exactly 13 weeks or 91 days long. What is to be done with Year Day is still up in the air— some have agreed to close down businesses as a holiday on Year Day to keep the round 364-day count (although this poses a problem on its own).

Issues with the Cotsworth calendar

Of course, this jarring of a change comes with its share of issues. Everything has its issues, and the Cotsworth calendar is no exception. One of the first things you may notice is that most days (all except for the first 28 in January) will have to shift. Some may even move into different months. This is a very large problem, as some holidays (especially those which are traditionally associated with their month of celebration) along with birthdays may move months. Independence Day, colloquially referred to as the Fourth of July, lies on Sol 17th in the Cotsworth calendar, which— well, just doesn’t have the same ring to it. With this, birth certificates, among other documents, will have to change to adapt to the new calendar system, and everyone born outside the first 28 days of January will have a different birthday, a change that would be super difficult to implement with the nearly 8 billion people on the planet. Every single date recorded in history will also have to change, which could cause historical and religious turmoil.

The distance between holidays is generally close year-by-year as well. The distance between Christmas and New Years is always a week, but with the Cotsworth, that week is reduced to just 4 days, since the month ends on the 28th. Between Thanksgiving and Christmas is only 27 days, whereas it can go to 32 on some Gregorian years.

Less of a problem but still existent is the start of seasons. Since the Gregorian calendar is more or less built around the rotation of the Earth, it aligns relatively well with seasons. Seasons start right after their respective solstice or equinox, which lands around between the 19th to 21st of either December, March, June, or September. However, this alignment is destroyed with the Cotsworth calendar. Winter’s start date is between December 17th and 19th; spring’s is between March 22nd and 24th; summer’s is between Sol 2nd and 4th (the start date actually moves months); fall’s is between September 10th and 12th.

Most of these problems boil down to adaptation. If we didn’t have so much technology and whatnot relying on the current time system, a switch could actually be reasonable.

The Cotsworth for businesses

However, switching to the Cotsworth doesn’t have to be for everyone. Recall that for nearly 60 years, Kodak used the Cotsworth within their company as their primary choice of calendar system. Having everyone change to the Cotsworth would be an extremely cumbersome process, but having companies choose the Cotsworth over the Gregorian for timekeeping purposes could provide benefits without giving too much up.

Since things like work and paying schedules work well with round numbers, the Cotsworth would provide an intrinsic obvious benefit. Not even everything in the company has to switch to the new calendar system. Just having work and pay schedules centered around the Cotsworth would provide a large benefit, as they are two of the most time-sensitive and round-number-sensitive things that wouldn’t break a ton of infrastructure to change. Also, since the day on which holidays don’t really matter in terms of the work schedule, (as much as they do culturally, at least— since people can just revert to the Gregorian after work and take days off according to that) there isn’t much of a downside.


While the Gregorian has been the global standard of calendar for centuries, it is not the most efficient calendar system out there. Being a calendar that has built on top of a calendar built on top of other calendars, it is a 12-month mess with differing days between each month. But in comes the Cotsworth calendar, or the International Fixed Calendar: a system in which there are 13 months of 28 days with one day at the end designated as “Year Day”. The Cotsworth is very friendly when dealing with numbers— its 4 weeks per month allow fiscal quarters to be divided easily and for months to all have an even amount of days (save for leap years). It was used at Kodak for 61 years as a “factory calendar” until 1989, with the easy, divisible units that come with it.

However, nothing is free of issues. Changing calendar systems for the entire world would be entirely impossible, especially in a world that is so deeply connected with technology and computers, for which keeping exact time is essential. Changing dates of birthdays and holidays would be completely out of the question, as well.

Also however, just switching calendars on the business side like Kodak did might be a good idea. When considering only that, the disadvantages start to get drowned out by the benefits. Maybe if the IFC was proposed in a time where we weren’t so reliant on computers, I could be writing this on Sunday, the 15th of December, the thirteenth month.

Thanks to Eric Rothermel, Roman Bozhko, and Omar Al-Ghosson for their stock imagery.