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Sources and Licenses

Every official date on calendarowl comes from the source below. Last full check: October 17, 2026. We copy facts (dates) only, never the layout, text or documents of a source, and we do not use any logos or seals.

United States

  • Federal holidays: U.S. Office of Personnel Management, Federal Holidays, based on 5 U.S.C. 6103. Works of the US federal government are in the public domain (17 U.S.C. 105).
  • Bank closures: Federal Reserve Board, Holidays Observed by the Federal Reserve System.
  • Post offices: U.S. Postal Service newsroom, holidays. The 2027 schedule had not been published when we checked; 2027 entries follow the rule used in 2026 and are marked "expected".
  • Stock market holidays and early closes: the holiday calendar published by the New York Stock Exchange.
  • Federal pay periods: USDA National Finance Center, 2027 pay period calendar. Federal fiscal year: 31 U.S.C. 1102.
  • Retail 4-5-4 fiscal calendar: dates from the merchandising calendar published by the National Retail Federation.
  • School district calendars: each district's own published calendar, linked on the page that uses it. We record dates only, read on two official documents, and do not host district files.
  • Catholic liturgical calendar: U.S. Conference of Catholic Bishops, Liturgical Calendar for the Dioceses of the USA 2027 (dates and ranks).

Other countries

  • United Kingdom: GOV.UK, UK bank holidays. Contains public sector information licensed under the Open Government Licence v3.0.
  • Canada: Government of Canada, federal labour standards and the employment standards pages of Ontario, British Columbia and Alberta; Quebec rules as summarized by Éducaloi, with dates checked against a Quebec government holiday calendar.
  • Australia: the public holiday pages of the governments of New South Wales, Victoria, Queensland and Western Australia; school terms from the Queensland Department of Education.

Calculated dates and software

  • Moon phases, seasons, Lunar New Year and the start of Islamic months: calculated with Astronomy Engine by Don Cross (MIT License). Islamic dates are approximate and may differ by one day.
  • Jewish holidays: calculated with the published arithmetic rules of the Hebrew calendar (our own code).
  • Easter and moveable feasts: the Gregorian computus (our own code).
  • PDF files: pdf-lib and fontkit (MIT License). Site: Astro (MIT License). Typeface: Manrope (SIL Open Font License), served from our own server.