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OLMExport

Export the calendar from an .olm archive

Meetings, appointments and their notes sit in the archive in Outlook's own XML. ICS is the calendar interchange format every calendar application reads, so one conversion puts years of appointments back on a calendar you actually use, which matters when the archive is the only copy of who met whom, and when.

The file you get

One .ics file with a VEVENT per appointment: start and end in UTC, title, location, organiser, attendees, description, and the recurrence rule where the event had one.

Steps

  1. Get the .olm out of Outlook for Mac first: Tools tab → Export, tick what you want, Continue, save the file. If Export is greyed out you are in the new Outlook; switch the New Outlook toggle off, top right, and it comes back. Tick Calendar in the export dialog.
  2. Drop the .olm on this page. It is read by JavaScript in your browser tab; the file never leaves your machine.
  3. Choose Calendar and download the .ics.
  4. In Apple Calendar: make a new calendar first if you want the events kept apart, then File → Import, pick the file, choose the destination calendar, click OK. Dragging the file onto Calendar does the same thing.
  5. In Google Calendar: Settings → Import & export → Import, pick the file and the target calendar.

What carries over

  • Title, start and end time, all-day flag
  • Location
  • Organiser and the attendee list as the archive recorded it
  • The event's notes as the description
  • Recurrence rules, where the archive stored them

Good to know

  • Times are written in UTC with a Z, which is what the standard asks for; your calendar app converts them to local time on import. Events from years with different daylight-saving rules can land an hour out, check a couple of old entries before you rely on them.
  • Importing into Apple Calendar clears an event's custom colour; colour is a property of the calendar you import into.
  • Attendee responses (accepted, declined, tentative) are not reliably present in the archive, so treat the attendee list as "who was invited", not "who came".
  • Reminders and alarms are not exported in this version.
  • Microsoft has never published the .olm format. Mail, attachments, contacts and calendar entries are read from the XML Outlook writes; unusual items (notes, tasks, journal entries) are skipped in this version.

Questions

Should I import into my main calendar?
No. Make a new calendar named something like "Outlook archive" and import there. Old events mixed into a live calendar are tedious to unpick, and a separate calendar can be hidden with one click.
Will it re-invite everyone?
No. Importing an .ics writes events locally; it does not send meeting invitations.
My recurring meetings look wrong.
Recurrence is where calendar formats disagree most. Check a recurring series after import, and if one is wrong, delete it and recreate the pattern by hand, it is the one part of a calendar import worth verifying rather than trusting.
Can I import only one year?
Yes, set the date range before exporting; only events in the range are written to the file.

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