A Suggestion for Replacing the Gregorian Calendar

In 2009 Tantek Çelik published a draft of a new calendar with 5-day-weeks solving issues with the Gregorian one.

I am not convinced, that this is a useful way to re-structure the calendar. Back in the days we set up a calendar for our RPG world together with Sebastian Gerstl and Markus Biedermann, which makes transition much smoother. We came up with this concept:

  • introduce a 13th month
  • distribute 7-day weeks evenly on the months
  • keep the 365th (or first) day of each year separately, together with the potential leap day and make it a “hooray, we have a useful calendar” holiday
schema of the new calendar


  • Remaining with the 7-day week makes the new calendar having very little impact on day-to-day live. And changing number of days in weeks hasn’t worked once, so I question it working now
  • Each month has exactly 4 weeks and 28 days, the “jumpiness” is reduced to one (two in leap years) single day
  • One new holiday!


None too serious.

  • Having introduced the 13 might frighten some Western esoterics. But on the other hand people get along quite well with each month’s 13th
  • Splitting the year in two is not possible with full months only. However, it is possible with exactly 6½ months, which is a clear advance over the Gregorian Calendar. (Also a quarter of a year is exactly 3¼ months or 3 months and 1 week.)
  • Being in the middle between sidereal and synodic month will be no real issue (sorry, astronomers)
  • Someone will have to name the new 13th month. While an UNO resolution is clearly the right way to go, it also means, that the new calendar will never be installed