Data sources and methodology
See how time zones, ISO weeks, calendars, solar times and public holidays are calculated, sourced and labelled.
Time zones
Live clocks and conversions use the browser’s implementation of the IANA time-zone database. Named zones allow offsets to change for the selected date.
Public holidays
Holiday dates are curated during the site build from the official or statutory source linked on every country-year page. The resulting lists are embedded in the HTML and in a same-origin data file; no third-party holiday API is contacted by visitors. Confirmed and rule-based dates can be used by the calculators, while provisional dates are displayed for context and deliberately excluded. Regional, proclaimed and lunar-observation dates should still be checked locally.
Weeks and calendars
Week pages use ISO 8601: Monday is day one, and week 1 contains the first Thursday of the ISO week-year. Calendar grids are generated statically and work without JavaScript.
Sunrise and sunset
Solar times are calculated in the browser from latitude, longitude, date and the standard 90.833° sunrise/sunset zenith, then formatted in the location’s IANA time zone. Terrain, elevation and buildings can change the moment the sun is physically visible.