Week and Month Calendar

I've been considering what would be a good calendar for calendar reform, where each date in the reformed calendar occurs on the same day of week every year. I've come to the conclusion that such a calendar needs to be a leap week calendar. Also I have come to desire a leap week calendar with months, where the leap week belongs to a month like the other months and furthermore that the week is a subdivision of the month. This means that no day of month number is necessary, saving one from having to remenber the day of month number, which is the trickiest part of the date to remember. Instead of a day of month number, the calendar date has a week of month name accompanied by a day of week name.

The year has twelve months, each with the same name as the Gregorian month that occurs at about the same time. Each month has either 4 or 5 weeks, which are named after letters of the Greek alphabet from Alpha to Delta or Epsilon. I have decided to name each week of month rather than number it, because a number could be confused for a day of month number or an ISO week number.

I've given five weeks to February, May, August & November and in a year with a leap week also December. This places the months closest to their Gregorian counterparts, while maintaining a regular quarterly pattern.

The calendar is based on the ISO week numbering, which has formed a de facto leap week calendar. ISO Week 1 is the week beginning Monday that contains the first Thursday of the Gregorian calendar year. It is also the week that begins with the nearest Monday to Gregorian January 1. Consequently, a year has exactly 52 weeks (364 days) if the corrsponding Gregorian year has 52 Thursdays or 53 weeks (371 days) if the corresponding Gregorian year has 53 Thursdays.

I could have chosen the leap week calendar formed from ISO week numbering (referred to as ISO Week Date) for calendar reform, but this calendar seems barren and has a week number, which is hard to remember. So I chose to have months as well as weeks and call the calendar the Week and Month Calendar.

Concise Definition

The calendar groups weeks into months according to their ISO week numbers as follows:

Weeks 01-04 January (4 weeks)   Weeks 05-09 February (5 weeks)   Weeks 10-13 March (4 weeks)
Weeks 14-17 April (4 weeks)     Weeks 18-22 May (5 weeks)        Weeks 23-26 June (4 weeks)
Weeks 27-30 July (4 weeks)      Weeks 31-35 August (5 weeks)     Weeks 36-39 September (4 weeks)
Weeks 40-43 October (4 weeks)   Weeks 44-48 November (5 weeks)   Weeks 49+   December (4 or 5 weeks)
The weeks of each month are named as follows:
First week of month:  Alpha
Second week of month: Beta
Third Week of month:  Gamma
Fourth Week of Month: Delta
Fifth Week of Month:  Epsilon (if month has 5 weeks)
Dates are formed from the Day of Week, Week of Month, Month & Year. For example Gregorian Thursday, 10 January 2019 would be Thursday Beta January 2019. Dates may also be formed in reverse order; eg. 2019 January Beta Thursday or be abbrievated to numbers in either order; eg. 4/2/1/2019 or 2019-01-2-4.

Years are numbered as the Gregorian year of its Thursdays.


The calendar replaces each ISO week number with a name made from a week of month name and a month name as follows:

01: Alpha January    14: Alpha April     27: Alpha July      40: Alpha October
02: Beta January     15: Beta April      28: Beta July       41: Beta October
03: Gamma January    16: Gamma April     29: Gamma July      42: Gamma October
04: Delta January    17: Delta April     30: Delta July      43: Delta October

05: Alpha February   18: Alpha May       31: Alpha August    44: Alpha November
06: Beta February    19: Beta May        32: Beta August     45: Beta November
07: Gamma February   20: Gamma May       33: Gamma August    46: Gamma November
08: Delta February   21: Delta May       34: Delta August    47: Delta November
09: Epsilon February 22: Epsilon May     35: Epsilon August  48: Epsilon November

10: Alpha March      23: Alpha June      36: Alpha September 49: Alpha December
11: Beta March       24: Beta June       37: Beta September  50: Beta December
12: Gamma March      25: Gamma June      38: Gamma Septamber 51: Gamma December
13: Delta March      26: Delta June      39: Delta Septamber 52: Delta December
                                                             53: Epsilon December

While using the calendar, I found it useful for calculating the current ISO week number.

Month Display

A typical four-week month could be displayed as follows. The blank space for each day can be filled with information about that day.

January Mon Tue Wed Thu Fri Sat Sun

A five-week month would have an additional row for the Epsilon week.

Birthdays and Holidays

The Week and Month calendar has completely different dates from the Gregorian calendar. It is therefore impossible to celebrate a birthday or holiday on the same date in this calendar as in the Gregorian calendar.

To work out when to celebrate a birthday in this calendar, work out the date of birth in the calendar and then use that date for the birthday. For example, if the date of birth were Wednesday, March 25, 1970, it would be Wednesday Delta March 1970 in the Week and Month calendar and so the birthday would celebrated on Wednesday Delta March. If one prefers to celebrate at the weekend, one can then have birthweek celebrations at the weekend of Delta March.

Similar considerations apply to holidays that are the anniversary of an event. For example July 4, 1776 would be Thursday Alpha July 1776, so "The fourth of July" would be celebrated on Thursday Alpha July, which is fortunately the fourth day of July. Holidays that always occur on the same day of week would always occur on the same date every year. For example, thanksgiving would be on Thursday Delta November.

Suggestion for Christmas and Easter

Christmas could be a variable holiday that is fixed to Gregorian December 25. If the previous year had no Epsilon December week, Christmas would occur one day later than last year, if this year is not a Gregorian leap year or two days later than last year, if this year is a Gregorian leap year. If the previous year had an Epsilon December week, Christmas would occur one week earlier than if last year had no Epsilon December Week. Furthermore, December has an epsilon week, if and only if, Christmas occurs on Friday Delta December or later.

Easter can occur on the same day as in the Gregorian calendar. The rule for calculating Easter can be reworded, so that "March 21" is replaced by the day 9 months and 6 days before Christmas Day. Easter would then occur on a Sunday from Gamma March to Gamma April inclusive or very rarely on Sunday Delta April.

The calendar does not forbid a fixed Christmas or Easter, if that is preferred.

Copyright 2018 Karl Palmen
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