MundoKit

Meeting time zone and DST checker

Enter the organizer’s first local date, time and IANA zone, then list participants and their work hours. Preview weekly meetings across upcoming clock changes.

Preview up to 50 weekly meetings for up to 12 participants. JavaScript is required. Calculations stay in your browser.

How it works

Local-time mode advances the organizer’s calendar date by seven days and resolves the same wall-clock time again. UTC mode resolves the first meeting once and adds seven 24-hour days for each occurrence. Participant dates, times and offsets come from Intl.DateTimeFormat. There is no time rounding; inputs and output use whole minutes.

The checker compares each participant’s UTC offset with their previous scheduled occurrence. Work status uses that participant’s local weekday and a start-inclusive, end-exclusive work window. It checks the meeting start only, not its duration. It does not import public holidays.

IANA maintains civil-time rules, but this tool uses the browser’s installed data rather than bundling a database. The browser does not expose a reliable database version. Updates to laws may therefore appear late; verify recent changes with the location’s official time authority.

Worked examples

New York stays at 09:00 while London shifts

For weekly meetings on 2, 9 and 30 March 2026 at 09:00 in America/New_York, Europe/London sees 14:00, 13:00 and 14:00. US daylight saving begins on 8 March; the UK changes on 29 March.

Keep the UTC anchor instead

Start on 2 March 2026 at 09:00 in New York, equivalent to 14:00 UTC. With a fixed UTC anchor, the 9 March occurrence is still 14:00 UTC, but New York sees 10:00 and London sees 14:00.

Frequently asked questions

Why does a recurring meeting move for only some people?
Locations can change their clocks on different dates or never change them. A fixed organizer time can therefore correspond to a different UTC time or participant time later.
What happens to a time that does not exist?
In local-time mode, an occurrence in a spring-forward gap is listed as skipped, without silently moving it. UTC mode requires a valid first instant and then continues at fixed intervals.
What if the organizer’s time occurs twice?
Choose the earlier or later instant, or leave the default flag-only policy. A flagged occurrence has no participant times until you choose a policy. The policy applies to every repeated organizer time in the series.
Can I use a Sunday–Thursday workweek?
Yes. Enter 71234 for that participant. Digits run from Monday=1 to Sunday=7. Work windows must start and end on the same local day; overnight shifts are not supported.
Does this include current time-zone data?
It uses the data installed with your browser or operating system, not a bundled or version-pinned copy. Supported dates are 2020–2035, including the final occurrence. Update your software and confirm newly changed rules before scheduling.

Sources

Last reviewed 2026-11-14; next review due by 2027-02-12. The method is written out above so you can check our math.