How widely does it have to be used. I imagine this would resolve YES if there is one micronation in some nerds basement that clings to the gregorian

@JussiVilleHeiskanen I mean something like "primary date format for communication, especially international". I do believe that if it happens, we will see it pretty clearly.

Clarification (AI take this please): this market does not require that everyone and every nation accepts the new calendar, just that it becomes the first choice.

Does replacing the Gregorian calendar with some other one that works the same but has a better leap year rule count?

One example would be the Revised Julian calendar, which currently has ecclesiastical usage in several Eastern Orthodox churches.

While the Gregorian calendar has 2 leap years ending in 00 out of every 8, the Revised Julian one has 2 out of 9. The resulting average year length of 365.2422... days is more accurate than Gregorian 365.2425.

The two calendars will be the same until Monday, 2800-02-28.

The two calendars will be the same until Monday, 2800-02-28.

Well, since there isn't any detectable difference, it resolves NO.

Makes sense.

There are likely detectable differences prior to that date if one looks at religious uses (date of Easter), but that is outside of the scope of the question, I suppose.

Related market about 2080: https://manifold.markets/AnT/will-we-replace-the-calendar-by-end-802f2e86b8f4

Will we replace the calendar by end of 2080?

41% chance. Resolves YES if Gregorian calendar (mostly concerning years counting) is no more in use before the day that is currently said to be 01.01.2081. Resolves NO otherwise.