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Calendar

How the calendar works

Each day keeps the calendar it belongs to. Its Gregorian date is computed from a rule for every year. Nothing is typed by hand and nothing is fetched.

Before you begin IDCDC is a peer-to-peer network. It is not a university and acts for no government, party, corporation or faith body.

Outside sources keep their own licences. A listing or a link is not an endorsement.

How this page handles evidence

Every figure carries its measure, year, source and label. Unknown is shown as unknown.

Verified
A label: the item matches its primary record, such as the official table or the Crossref entry.
Secondary source
A label: the figure comes from a reliable report about the source, not from the source itself.
To verify
A label: the item is listed as found and still needs checking against its source.

Sources

No source is attached yet. Sources are added at review.

Cite this page

Report an error What we are and are not

01Four kinds of entry

Community days
The community’s festivals, remembrance, religious and civic days. Each cites scholarly or official sources, or says that its citation is in preparation.
International days
The days and weeks of the official UN list, with their resolutions. The faculties and disciplines beside each are the platform’s editorial mapping, a proposal for review.
Public holidays
Official public holidays per country and ISO 3166-2 subdivision. They come from a register source, and only once the owner approves it.
Programme events
Confirmed convenings of the network, and community events shared through contributions after a check.

02The calendars

Gregorian
Fixed days, such as civic and remembrance days.
Solar Hijri
The calendar of Iran and Afghanistan. The year begins at Nowruz, on the day of the March equinox if it falls before noon in Tehran, otherwise the next day. Dates use the Unicode CLDR Persian calendar. A test checks it against the astronomical rule for every year shown.
Lunar Hijri
Dates follow the Umm al-Qura tables of Unicode CLDR. A local sighting of the new moon can differ by a day, so communities may mark a day earlier or later.
Julian
The Yazidi year follows the Julian calendar, now 13 days behind the Gregorian.
Astronomical
Equinoxes and solstices are computed with the method of Jean Meeus, Astronomical Algorithms (1998), to within a minute.
Set each year
Some days are set each year by an authority or by local custom. They are not computed. Where the authority publishes the dates, the page shows them as published.

03Equinoxes and the new year

Computed for every year of the calendar. Times are to the minute.

YearMarch equinoxIn Tehran1 Farvardin by the astronomical ruleDecember solstice
20262026-03-20 14:45 UTC2026-03-20 18:15 TehranSaturday, 21 March 20262026-12-21 20:50 UTC
20272027-03-20 20:24 UTC2027-03-20 23:54 TehranSunday, 21 March 20272027-12-22 02:42 UTC
20282028-03-20 02:17 UTC2028-03-20 05:47 TehranMonday, 20 March 20282028-12-21 08:19 UTC
20292029-03-20 08:01 UTC2029-03-20 11:31 TehranTuesday, 20 March 20292029-12-21 14:14 UTC
20302030-03-20 13:51 UTC2030-03-20 17:21 TehranThursday, 21 March 20302030-12-21 20:09 UTC

04Where a day falls in any year

Heritage · the calendar’s model

From a festival to a date: where a day falls in any year

Each day keeps the calendar it belongs to. Choose a day and a year to see it in the Gregorian, Solar Hijri and Lunar Hijri calendars.

  • Data
  • Model
  • Gate
  • Outcome
DayCalendarsDayNowruzCalendar ruleSolar Hijri dateYear2026Gregorian dateSaturday, 21 March 2026Solar HijriFarvardin 1, 1405 APLunar HijriShawwal 2, 1447 AHWeekdaySaturday
Gregorian date
Saturday, 21 March 2026
Solar Hijri
Farvardin 1, 1405 AP
Lunar Hijri
Shawwal 2, 1447 AH
Weekday
Saturday

The platform’s calendar; date arithmetic from Unicode CLDR via the reader’s browser.

05Labels and sources

  • Verified: checked against the official page on the date given.
  • Secondary: a scholarly reference work.
  • To verify: not yet checked against an official or scholarly source.
  • Contested days show every side with its sources. The calendar endorses no party, faction or armed actor.

Report a correction

06Cities and subdivisions

  • Subdivision dates come with the public holidays, by ISO 3166-2 code.
  • City dates come only from official city sources, such as a city’s open data. None is held yet, so city calendars say forming.
  • Each country, subdivision and city page carries the calendar for its place.
Cite this page
APA

Iranian Diaspora Cooperation & Development Council. (2026). About the calendar. iranians.global. https://iranians.global/heritage/calendar/about/

Chicago

Iranian Diaspora Cooperation & Development Council. 2026. “About the Calendar.” iranians.global. https://iranians.global/heritage/calendar/about/.

BibTeX
@misc{idcdc2026_heritage_calendar_about,
	author = {{Iranian Diaspora Cooperation \& Development Council}},
	year = {2026},
	note = {Licence: CC BY 4.0},
	title = {About the calendar},
	url = {https://iranians.global/heritage/calendar/about/},
	howpublished = {https://iranians.global/heritage/calendar/about/},
}

Download .bib

RIS
TY  - ELEC
AU  - Iranian Diaspora Cooperation & Development Council
DA  - 2026///
PY  - 2026
ID  - idcdc2026_heritage_c
N1  - Licence: CC BY 4.0
TI  - About the calendar
UR  - https://iranians.global/heritage/calendar/about/
ER  -

Download .ris

Licence CC BY 4.0