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Symmetry010 Calendar

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Wikipedia-logo-en This page uses content from the English Wikipedia. The original article was at Symmetry010 Calendar. The list of authors can be seen in the page history. As with the Calendar Wikia, the text of Wikipedia is available under Creative Commons License. See Wikia:Licensing.


The Symmetry010 Calendar (Sym010) is a proposal for Gregorian calendar reform developed by Dr. Irv Bromberg of the University of Toronto, Canada.

It is a perpetual solar calendar that conserves the traditional 7-day week, and has symmetrical equal quarters of 30+31+30 days each. Unlike its sibling system and successor, the Symmetry454 Calendar, it does not start every month on Monday, but has month lengths closer to the traditional ones. It is retained as an alternative for those who think that the Sym454 design is too "radical" a departure from the Gregorian calendar format.

In a leap year, the Symmetry010 leap week is either appended to December, making it a 37-day month, or it can stand alone at the end of the year as a 13th "mini-month" that was dubbed "Irvember" by Yoel Berznoger of Toronto.

The Symmetry010 calendar is demonstrable in Kalendis by choosing 30+31+30 quarter structure in the Symmetry calendar window. The user can also choose the desired handling of the leap week from the "Symmetry Leap Week" submenu of the "Options" menu. The Sym010 calendar arithmetic is also documented in the public domain, alongside that of the Sym454 calendar.

Symmetry010 year layout
Quarter 1st month 2nd month 3rd month
1st
January
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30
February
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
March
Mon Tue Wed Thu Fri Sat Sun
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
2nd
April
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30
May
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
June
Mon Tue Wed Thu Fri Sat Sun
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
3rd
July
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30
August
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
September
Mon Tue Wed Thu Fri Sat Sun
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
4th
October
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30
November
Mon Tue Wed Thu Fri Sat Sun
1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31
December
Mon Tue Wed Thu Fri Sat Sun
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31 32 33 34 35 36 37

(The last 7 days of December, shown in grey, are intercalary days that are appended only to the end of leap years.)

Background Edit

Balanced quarters are desirable for businesses because they aid in fiscal planning and analysis.

All holidays, birthdays, anniversaries, etc. are permanently fixed. All ordinal day and week numbers within the year are also permanently fixed.

"Friday the 13th" never occurs.

Leap Rule, Arithmetic and EasterEdit

See Symmetry454 Calendar

External linksEdit

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