Local sustainability

The Fixed Calendar

Fixed Calendar © 2021 by Simon D. Cole is licensed under Creative Commons BY-NC-SA 4.0

The Fixed Calendar simplifies dates and accounting because every month has the same number of days. Also, dates and days of the week are fixed. The same calendar can be used every year! The main difference is the extra month of Sol in the middle and the “intercalary days” (Year Day and Leap Day) that are outside the week days.

There are two compelling advantages to the Fixed Calendar. 1/ Business accounting is more accurate. 2/ Ordinary people can memorize it (see below).

I got tired of having to check the Gregorian calendar every fortnight to keep up with the date of rental payments. There had to be a better way, I thought. A little research revealed someone had already solved the problem. I adopted Moses B. Cotsworth’s International Fixed Calendar (see below) and incorporated the Gregorian calendar to create a conversion table (above). The watermark shows the Gregorian months (not dates). I call it the Fixed Calendar. I use it for in-house book-keeping. Keep a copy handy for quick, easy reference.

The original International Fixed Calendar is a solar calendar proposal for calendar reform designed by Moses B. Cotsworth, who presented it in 1902: Wikipeadia explains the pros and cons of the International Fixed Calendar and calendar reform proposals in general. Kodak company is famous for having used it for 60 years.


My conversion table shows how distorted the Gregorian calendar is in comparison to a fixed calendar. There are three more days in the second half of the Gregorian year than the first half! The Fixed Calendar solves this.


The Gregorian calendar quarters are not equal, as shown in the comparison table below.

QuarterGregorian CalendarFixed Calendar
1stJanuary to March= 90 daysJanuary to April 7th= 91 days
2ndApril to June= 91 daysApril 8th to Sol 14= 91 days
3rdJuly to September= 92 daysSol 15 to September 21= 91 days
4tfOctober to December= 92 daysSeptember 22 to December 28th= 91 days
Quarters compared: Gregorian vs Fixed

This has significant on-going consequences for accounting in business and government financing. Here are some real world examples. The Fixed Calendar quarters do not coincide with whole months as in the Gregorian calendar. However, quarters are used mainly by accountants, whilst fortnights are more familiar to wage-earners and renters. Quarters that don’t coincide with months are no impediment to the numerate. Therefore, I contend that the Fixed Calendar has wider appeal than the World Calendar, which is also a fixed calendar, with 12 familiar months. I contend that it is easier to learn a new month, than memorize the irregular number of days in the months of the World Calendar.

The irregularities of the Gregorian calendar is the reason we can’t memorize it.

Why a calendar we can memorize?

There are two considerations. One, our reliance on paper and Internet-based diaries and calendars becomes virtually unnecessary to remind us of what the date is. They are useful for long-term planning. Our resilience as a society in the face of potential disruptions to the digital age from electro-magnetic bombs and solar flares is strengthened. Two, the affect on our brains of out-sourcing everyday functions is in question. Studies show our memories can be impaired (Johansson, A). We can lose skills, too, such as using maps. Personally, turning to a smart phone for calendar, spelling and directions assistance makes me feel sleepy and dependent. There is something spiritually depleting to be unable to act without them, or rather, to not use the capacities I have. Anna Johansson puts it well in her article We need to reduce our dependence on technology if we want to keep innovating:

Instead of introducing a gradual improvement or iterative form of assistance, we’re overwriting entire functions of our brains and bodies. As a metaphor, shoes serve to protect your feet from the dangers of walking on questionable terrain, but if you rely on a wheelchair when you don’t truly need one, your leg muscles would eventually atrophy.


In a sense I am acting in the interests of everyone when I call for changes to our human environment that enable us all to operate in it with unneccessary aids.

Since the Information Revolution, calendar (and spelling) reform movements have receded into the background. Smart phones among other devices, have taken over the memorizing for us. Few people born after the 1990s have lived without the aid of technology and therefore barely notice the inconvenience of the Gregorian calendar. Reform movements have evolved in response to changes in power structures and modern technology, which has made innovation more distributed. While once it was governments that debated calendar and spelling reform, now these changes are coming directly from the general public. However it seems some of these technologies are actually serving to stifle innovation of some internationalized habits such as calendars and spelling. The conversion table I’ve created is for grass-roots change-makers. If it works for you, use it!

Fun facts:

  • Although the Fixed Calendar is a solar calendar, not a lunar calendar like the Islamic calendar, it follows the cycles of the moon more closely than the Gregorian calendar.
  • Weeks are unrelated to astronomical phenomenon. They are purely a human construct for dividing months into shorter, more manageable time periods. Sumerians had 10 day weeks, but 7 day weeks became the norm in ancient Israel, and it took off from there.
  • The Fixed Calendar has 13 Friday the 13ths, throwing down the gauntlet to the superstitious! .
  • Sol means Sun and is northern hemispheric centric.
  • Others have created conversion tables – see the one by freexenon.com.

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