Calendar

Mostly from the open Nager.Date dataset, supplemented per country where that dataset is thin or wrong: China comes from the State Council's published arrangement so the make-up working days are included, and a handful of countries are curated by hand against official sources.

Five: the current year and the four after it, for most of the countries covered. A few carry fewer because their official calendar simply is not published that far ahead — those years stay empty instead of being estimated. China is the notable case: its statutory holidays are fixed by regulation, but the annual 调休 arrangement that turns them into long weekends is decreed only about a year in advance, so future years show the 13 statutory days with a note saying the adjustment is still to come.

The canonical date of the holiday itself. Where a country grants a separate substitute day off — the UK and Ireland do this explicitly — that substitute appears as its own entry, so you see both the holiday and the day the offices are actually shut.

Because we would have to guess. Several calendars are lunar or decreed annually, and publishing an invented date for a holiday people plan travel around is worse than publishing nothing. Those countries are left blank until a sourceable calendar exists.