Calendar Wiki
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What Date Is It? Today's date and time in 101 different calendars.
About Calendar Wiki

This is a site all about calendars - historical ones, new ones, and discussions about them: for the scientist, astronomer and the calendar enthusiast.

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Featured Calendar
Flag of the International Calendar

The International Standard Calendar (ISC) is the subset of the International Calendar which is recognised by the International Standardisation Organisation in ISO 8601, parts 1 and 2. It builds upon the primary International Standard Month Calendar, which defines a year based on months and uses the (proleptic) Gregorian leap day rule for a 400-year leap cycle. The alternative International Standard Day Calendar just places the leap day at the end of the year. The secondary International Standard Week Calendar uses the same year count but subdivides a year into 52 weeks and occasionally a 53rd one.

The ISC lacks the Gregorian Easter Computus, or really any consideration of lunations. With EDTF support in ISO 8601-2, it does cover seasons and groups of months, e.g. quarters, on a very basic level. The International Calendar contains more notation variants and auxiliary calendars, such as quarters, full-week months, seasons, shifts and placeholders.

Where to start
  • What is a calendar? Stop by our general article to find out.

Here are some good places to start learning about calendars:

User blogs


Crissov Crissov 4 May 2023

Possible dates for a fixed Easter

The date of Easter and its lunisolar computation Computus is of central importance to many Christian churches. It is historically linked to the Jewish holiday of Pessach, Passa or Passover, which begins th…

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Arivumani1 Arivumani1 30 March 2020

New Weekdays for Perpetual Calendars

Today we are using Classical planets, Sun, Moon, Mars, Mercury, Jupiter, Venus and Saturn as weekdays Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday respectively. Modern planets U…

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Loco123456 Loco123456 10 March 2019

Thomas and the Magic Railroad - The Lost Edition Petitoin: Please Sign

Hello everybody,

A nonprofit organization called "Restore the Magic" needs help in getting 10,000 signatures on their petition. The petition is to help get the director's cut of "Thomas and the Magic …

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