2020 Just Piles On: If you’re looking forward to 2021, I have bad news


No, this is not another of my calendar reform rants. It’s about calendar reform that already happened.

Since 1971, the ISO standard calendar (ISO 8601) has been accepted worldwide and used in many systems and bodies: governments, business, accounting, UNIX and other computers, etc.  The standard was accepted primarily for financial systems, so that every year starts on a Monday.  There are no months in the ISO calendar, only weeks.  In 2015, a weekly numbering system was added, from 1 to either 52 or 53, depending on the year.

In the ISO calendar, the new year always starts on the Monday closest to January 1st, which can be up to three days before or after the actual date.  January 1st falls on a Monday four times every 28 years, but at intervals of 11, 6, 5, and 6 (2018, 2007, 2001, 1996, 1990, 1979, 1973, 1968, 1962, 1951, etc.).  The pattern is interrupted by a 12 year period (or 6 and 6) when the century is not a leap year (1906, 1900, 1894, 1883. . .1816, 1810, 1798, etc.).

In 2020 on the Gregorian calendar, Monday, December 27 is four days before January 1st (a Friday).

The first day of the ISO 2021 calendar is January 3rd.  

That means three more days of 2020.  Enjoy.


Tom Scott made a video about the ISO calendar on December 30, 2019.  If I believed in supernatural hokum, I’d say his words at 2:53 weren’t prophetic, they were a curse.

So, if 2019 has been a rough year for you, and you want to leave it behind, change calendars for a while. Welcome to the twenties.

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