Chronira
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Sources

These are the sources Chronira's calculations rely on: calendars, international standards and the laws that define public holidays. How each rule is applied is explained in the methodology.

Hijri calendar: Umm al-Qura

Hijri dates use the Umm al-Qura calendar, the official civil calendar of Saudi Arabia. Chronira does not keep its own copy of the calendar: it reads the Umm al-Qura data built into modern browsers through the Unicode CLDR and ICU (International Components for Unicode) calendar implementation. The supported range is 1300 to 1600 AH (1882 to 2174 CE). Many countries start Islamic months after an official moon-sighting announcement, so dates of Islamic occasions are always shown as expected.

ISO 8601 week numbers

Week numbers follow the international standard ISO 8601: weeks start on Monday, and week 1 is the week that contains the year’s first Thursday. ISO dates are also written in the YYYY-MM-DD form defined by this standard.

Gregorian calendar rules

All Gregorian dates follow the calendar’s leap-year rule: a year divisible by 4 is a leap year, except century years, which are leap years only when divisible by 400. The same rules are applied to dates before 1582, when the calendar was introduced (the proleptic Gregorian calendar).

Easter computus

Western Easter Sunday is computed with the anonymous Gregorian algorithm (also known as the Meeus/Jones/Butcher algorithm), the standard computus for the Gregorian calendar. French public holidays that depend on Easter (Easter Monday, Ascension and Whit Monday) are derived from it.

Public holidays and working time

Each holiday calendar in the business days calculator is defined from the official legal source listed below. US federal law (FLSA) general overtime rules are described by the US Department of Labor; overtime thresholds on Chronira are always your own inputs. Check your contract, employer or local law for the rules that apply to you.

The holiday calendars currently available, with their official sources and what each one covers, are listed below.

  • France (public holidays) — The 11 public holidays of the French Labour Code (art. L3133-1). Alsace-Moselle adds Good Friday and 26 December.
  • Germany (nationwide holidays) — The 9 holidays observed in every German state. States add their own (e.g. Epiphany, Corpus Christi, Reformation Day).
  • Norway (public holidays) — The 12 public holidays of the Norwegian Holidays Act and 1 and 17 May. Easter Sunday and Whit Sunday always fall on Sundays.
  • Spain (national holidays) — The national holidays of the Workers’ Statute (art. 37.2) shared by all regions. Regions can swap some of them and add their own.
  • United States (federal holidays) — The 11 federal holidays of 5 U.S.C. 6103, on their observed dates. States and employers may differ.

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