# Focus Room Countdown

> Time left until a moment in any time zone, with working days, holidays and a calendar file. Counts down to a date and time in any IANA time zone: days, hours, minutes and seconds left, calendar days and working days before the event day (weekends of your choice and public holidays of 16 countries skipped), daylight-saving changes on the way, the same moment on other clocks, and an .ics calendar event. The “New Year in every time zone” mode lists when midnight arrives from Kiritimati to Baker Island. The Focus Room app shows the same countdown full screen.

Part of usefulweb.app (https://usefulweb.app/). Part of [Focus Room](https://focusroom.usefulweb.app/) (ownerApp: focusroom). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://focusroomcountdown.usefulweb.app/ (interactive tool at https://focusroomcountdown.usefulweb.app/tool)
- JSON API: POST https://focusroomcountdown.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://focusroomcountdown.usefulweb.app/api/v1/tool)
- OpenAPI: https://focusroomcountdown.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://focusroomcountdown.usefulweb.app/mcp - tool `focusroom_countdown`

## Inputs
- event (select): Event
- title (text): Title
- target (datetime): Date and time of the event - Wall-clock time in the event’s time zone. Not used for New Year.
- zone (text): Time zone of the event - IANA time-zone name such as Europe/Berlin, America/New_York, Asia/Kolkata or UTC.
- from (datetime): Count from (optional) - Wall-clock time in the event’s time zone. Empty = now (rounded down to the minute).
- country (select): Public holidays - Holidays on weekdays are not counted as working days (data 2024–2030).
- subdivision (text): Region (optional) - ISO 3166-2 code such as DE-BY or US-CA for regional holidays.
- weekend (select): Weekend days
- otherZones (list): Show the moment in these time zones - One IANA name per line.
- alarmMinutes (integer): Reminder in the calendar file - 0 = no reminder.

## Method
- Time zones come from the IANA time-zone database through the platform’s Intl implementation. The event’s wall-clock time is converted to an instant by trying the zone’s offsets around it: a time that does not exist (the hour skipped when clocks go forward) moves forward by the gap, a time that happens twice (clocks go back) takes the earlier one; both cases are reported.
- Remaining time is the exact difference between the two instants, split into days of 24 hours, hours, minutes and seconds. Calendar days count from today’s date in the event zone to the event day.
- Working days count the dates from today (inclusive) up to the event day (exclusive) that are neither a chosen weekend day nor a public holiday of the chosen country (nationwide, or of the given region). Holiday data: RuleDate’s Nager.Date set for 2024–2030.
- New Year mode: for every time zone in the built-in list (each distinct UTC offset in use, from UTC+14 to UTC−12) the instant of local midnight on 1 January is computed and zones that share it are grouped.
- The .ics file follows RFC 5545 with the start in UTC, so calendar apps show it at the correct local time anywhere; UID and DTSTAMP are derived from the event, so the same input gives the same file.

## Limits
- Time-zone rules change from time to time; far-future countdowns follow today’s rules. Check holidays that matter (company closures, bridge days) yourself.