The 36-day month calendar is an experimental calendar, devised by Stephen Abbott, of 10 months of 36-days each.

The 10 months, January through October, total 360 days. The seven-day week is retained in this proposal, along with the names of the weekdays.

About every 7 years an additional 36-day month, a November "leap month," would be added. Every 14th, 21st, and 28th year, a leap day would be added to the November leap month, making it 37-days long.

No. Name Days
1 January 36
2 February 36
3 March 36
4 April 36
5 May 36
6 June 36
7 July 36
8 August 36
9 September 36
10 October 36
11 November 36* or 37**

* November is a leap month, occuring every 7th year
** November leap month has an extra day every 14th, 21st and 28th year of a 28-year cycle.

## Features

• The seven-day week retained, along with weekday names and the first 11 month's traditional names
• Months are all equal in length (36 days) in normal years and in one out of four of leap years, eliminating confusing differing month lengths
• Each month within a calendar year begins exactly one weekday after the previous month (i.e. if Jan. 1 is a Monday, Feb. 1 is a Tuesday, Mar. 1 a Wednesday, etc.)
• There are four equal 90-day quarters every normal year. In the first leap month, four 99-day quarters are possible. In other leap years, three 99-day quarters and one 100-day quarter occurs

## Drawbacks

• Years are not equal in length
• Calendar is not perpetual - Jan. 1 occurs on a different weekday each year
• With the rules described that calendar would have a mean year of 365 1/4 days, which is the same as for the Julian Calendar.

## Alternative Leap Year Rules

### 2800-year cycle

The rules are the same as stated above except that if a year with a leap month has a number ending with 00, it has a 36-day November, unless that year's number is divisible by 400. This rule is similiar to the Gregorian calendar leap year rule and produces exactly the same mean year of 365.2425 days. Note that the only leap year of the 28-year cycle that can end in 00 is the 28th year, which normally has a November of 37 days.

### 231-year cycle

One could have every leap month have 37 days except those in years whose number is divisible by three, but not also divisible by 11, where the leap month has 36 days. Then the mean year would be 365 8/33 days.

### 570-year cycle (All months with 36 days)

If you want every month to have 36 days without exception one could have a 570-year cycle, in which the following 83 years have a leap month, consisting of 36 days:

While an alternating 36-day month to a 37-day month would make more sense and would not have the need for a leap month. E.G January would have 36 days and February would have 37 and March would again be a month of 36 days and so on and on.

 001 008 015 022 029 036 043 050 056 063 070 077 084 091 098 104 111 118 125 132 139 146 153 159 166 173 180 187 194 201 207 214 221 228 235 242 249 256 262 269 276 283 290 297 304 310 317 324 331 338 345 353 259 365 372 379 386 393 400 407 413 420 427 434 441 448 455 462 468 475 482 489 496 503 510 516 523 530 537 544 551 558 565

Each row has leap years 7 years apart and they alternate between 55 and 48 years in duration. Also note 103-year cycle between alternate rows.