Symmetry454
| Epoch | Confidence |
|---|---|
| 1 January 1 CE | Exact |
Overview
The Symmetry454 calendar is a Gregorian-derived calendar proposed in 2005 by Irv Bromberg.
It features the same months as the Gregorian calendar but of different lengths, following a pattern of 28/35/28 days. This allows for a whole number of weeks in each month, 4/5/4 respectively, hence the calendar's name.
The calendar features a leap year that extends December by an extra week, occurring every 5 or 6 years. This keeps it in line with the Gregorian calendar on a 293-year cycle containing 52 leap years.
The format of the calendar allows each day of the year to always occur on the same day of the week.
Info
This calendar is calibrated using 1 January 2001 as a reference date.
| Months | Days |
|---|---|
| January | 28 |
| February | 35 |
| March | 28 |
| April | 28 |
| May | 35 |
| June | 28 |
| July | 28 |
| August | 35 |
| September | 28 |
| October | 28 |
| November | 35 |
| December | 28 or 35 |
Accuracy
As this calendar is only a proposal, there really isn't anything to compare it to historically. It is intrinsically based on and locked to the Gregorian calendar, making it perfectly accurate.
It has also been calibrated using the Kalendis tool which was created by the same creator of Symmetry454.
There are sources that list this calendar as meeting up with the Gregorian calendar on 1 January 2005 CE, but I believe this to be a typo. The dates line up on 1 January 2001 CE as well as 1 January 1 CE, which is the epoch in both calendars.
Source
Much of the information on this calendar came from its Wikipedia article.
This calendar has also been calibrated using a Windows app created by the creator of the Symmetry454 calendar, which can be found here.