How we calculate local times

Explanations and calculation

The guides explain 2026 clock changes using official sources. Tables are calculated during the build and included in the HTML. Interactive tools use Intl.DateTimeFormat and the browser’s time-zone data without calling an external conversion API.

Cities and supported dates

This edition supports 2026 dates and nine named cities: Madrid, Mexico City, Bogotá, Buenos Aires, Lima, Santiago, New York, London and Santa Cruz de Tenerife. Madrid represents mainland Spain; Mexico City and New York do not represent their entire countries.

Repeated and missing hours

The engine finds the instants matching a local date and time. Two matches allow first or second occurrence selection. No match produces a warning. A missing local time is never silently replaced with another.

Availability and weekly sessions

The planner checks each real minute of the chosen duration against local availability, including any transition inside the meeting. The weekly checker advances by seven calendar days in the origin zone and resolves the same local clock time separately for each date. An invalid session blocks complete export.

Calendars and links

Events store UTC instants without participants. The converter uses 60 minutes; other tools use the selected duration. Weekly export contains four or eight independent appointments, without an infinite recurrence rule. Downloads do not send invitations or update existing events. Shared URLs contain selected filters and can appear in hosting logs.

Limits and review

Authorities can change time-zone rules. An outdated browser may contain old data. Build-time tables use Node 24.18.0 with time-zone data 2026b. Editorial review is dated 20 October 2026; it is not continuous human monitoring. Confirm critical appointments with their organiser and report an error with the city, date, clock time and device.