CorrectICS

TZID=EST is invalid in an ICS file (what to use instead)

If you’re seeing TZID=EST (or TZID=PST, TZID=CST, TZID=GMT-5) inside an .ics file, that’s a strong sign your import issues (or wrong-time events) are caused by an invalid or ambiguous time zone identifier.

Fastest path:

  • Validate the file with the free ICS validator.
  • Upload to /fix to generate a repaired .ics when fixes are available.

Why EST is a problem in iCalendar

In ICS, TZID is expected to be an IANA time zone (the Region/City format), like:

  • America/New_York
  • Europe/London
  • Asia/Tokyo

Abbreviations like EST are ambiguous:

  • Do you mean Eastern Standard Time (no DST) or Eastern Time (with DST)?
  • Different systems interpret abbreviations differently.

That’s why Google Calendar and other clients may reject them or interpret them in a way that shifts event times.

What to replace EST / PST / CST with

Common replacements:

  • EST → America/New_York
  • PST / PDT → America/Los_Angeles
  • CST / CDT → America/Chicago
  • MST / MDT → America/Denver

If you’re not sure which zone is correct, check the event’s intended location and verify the imported time in multiple clients.

The “events at the wrong time” symptom

If your events are:

  • one hour off,
  • shifted to a different day, or
  • correct in one client but wrong in another,

start here:

Outlook note: VTIMEZONE may also be required

Even with a correct IANA TZID, some Outlook/Exchange flows are stricter about needing a matching VTIMEZONE block when local times are used.

If you’re seeing errors like “missing VTIMEZONE” (or imports that work in Google but fail in Outlook), see:

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