Import an ICS Calendar into Microsoft 365 Outlook

Import an .ics file when you need a one-off copy of its events. Subscribe to an iCal URL when the publisher will keep changing the calendar and you want Outlook to receive later updates. You do not need to convert an ICS file to PST for an ordinary calendar import.

Choose import or subscription first

These actions behave differently:

Import from file copies the events currently in the ICS file. Later source changes do not update those imported events.
Subscribe from web links Outlook to a published calendar URL. Outlook checks for changes, but updates are not immediate.

Microsoft's Outlook import and subscription guide documents both routes and warns that subscribed-calendar updates can take time.

Import an ICS file in Outlook on the web

Save the .ics file to your computer.
Sign in to Outlook on the web with the correct work or school account.
Open Calendar.
Select Add calendar.
Select Upload from file.
Browse to the ICS file.
Choose the destination calendar.
Select Import.

Check a sample of events after import. Verify dates, time zones, recurrence, locations and the destination calendar.

If you import the same file twice, Outlook can create duplicate events. Test with a separate calendar when the file is large or its quality is uncertain.

Subscribe to an online ICS calendar

Use this when you have an HTTPS calendar address rather than a downloaded file.

Open Calendar in Outlook on the web.
Select Add calendar.
Select Subscribe from web.
Paste the published iCal URL.
Give the calendar a recognisable name.
Select Import or Save, according to the interface shown.

A subscription is normally read-only in Outlook. Changes belong in the source calendar. The source owner can also remove or change the feed, so do not treat a subscription as a permanent archive.

Classic Outlook for Windows

Microsoft's current Outlook guidance documents this file route:

Select File > Open & Export > Import/Export.
Choose Import an iCalendar (.ics) or vCalendar file (.vcs).
Select the file.
Choose the import option presented by Outlook.

New Outlook and classic Outlook do not always use identical menus. Use the procedure for the client you actually run rather than following screenshots from an older edition.

Common failures

The time is wrong

The ICS file may contain UTC values, a named time zone or incomplete time-zone definitions. Inspect the source event and test around daylight-saving changes before a bulk import.

Events are duplicated

Importing is a copy operation. Delete the test calendar or remove duplicate items before trying again. Keep the original file until the result is checked.

Subscription changes do not appear

Subscribed feeds update on Outlook's schedule, not when you refresh the browser. Wait for the documented sync interval and confirm the source URL still serves valid ICS content.

Add calendar is missing

Expand the calendar navigation and confirm you are in the intended account. Organisational policy can limit calendar features, so ask the Microsoft 365 administrator before trying unsupported workarounds.

Migration boundary

An ICS file carries calendar events. It is not a mailbox migration package and does not include ordinary email, contacts, permissions or every Outlook-specific property.

For organisation-wide mailbox migration, use a separately planned Exchange Online migration route. Do not turn a simple ICS import into a PST upload or third-party conversion purchase without a requirement that justifies it.

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