How the calendars are made
A calendar on the fridge should be right. That is why every date says where it comes from.
Federal holidays
The 11 federal holidays are set by 5 U.S.C. 6103. When one falls on a Saturday, federal employees get the Friday before off; on a Sunday, the Monday after (Executive Order 11582). We checked every date from 2026 to 2030 against the holiday schedules of the U.S. Office of Personnel Management.
Other holidays and observances
Easter is computed with the Gregorian Easter formula; Good Friday, Ash Wednesday and Mardi Gras follow from it. Mother's Day, Father's Day, Election Day and daylight saving time follow their fixed rules. These days are not federal holidays and appear in a lighter style.
Moon phases and seasons
Moon phases are computed with Jean Meeus' Astronomical Algorithms and checked against all phases from 2026 to 2028 published by the U.S. Naval Observatory (same date, at most one minute apart). Equinoxes and solstices come from the U.S. Naval Observatory. All times are Eastern Time.
Checked with examples
Every rule has test cases with values read from the source or worked out by hand. They run with every change.
PDFs
The PDFs are generated from the same data as the pages, in US Letter and A4, with Sunday or Monday as the first day. They are free, also for schools, clubs and offices.
Who is behind it
calendarslip is a small, independent project by Daniel Lehner from Munich, Germany – the English sister of kalenderzettel.de. Found a mistake? kontakt@kalenderzettel.de
No warranty
Everything is carefully checked, but for information only and without warranty. Your employer, school district or state may observe other days.
Updated: November 2026