Which Method Fits Your Calendar?
To migrate an Outlook calendar to Office 365, use a PST file, an ICS file or a mailbox copy. The method depends on the source Outlook calendar and on the number of users.
| Method | Scope | Cost | Use case |
|---|---|---|---|
| PST file | One calendar | Free | Classic Outlook source |
| ICS upload | One calendar | Free | Any calendar app |
| Migration software | Many users | Paid | Cloud platform moves |
How does a PST File Move the Calendar?
Method #1: PST Export and Import (Free With Outlook)
Who it suits. Users who move an Outlook calendar from a computer. Extra application. Classic Outlook.
- Export the Outlook calendar from the source app with Open & Export, Import/Export and Export to a file.
- Save it as an Outlook Data File (.pst).
- Add your Office 365 account to classic Outlook.
- Select Import/Export and select Import from another program or file.
- Choose the PST file and select how to handle duplicates.
- Choose your Microsoft 365 mailbox as the destination.
The Microsoft import page lists the same wizard. Microsoft states that importing a calendar from a PST file is not supported in new Outlook.
The export side follows the Office 365 calendar to PST guide.
Can a Browser Upload a Calendar File?
Method #2: ICS Upload in Outlook on the Web (Free, Browser)
Who it suits. Users with an ICS file from any calendar app. Extra application. None.
- Save the Outlook calendar as an .ics file.
- Sign in to Outlook on the web and select Calendar.
- Select Add calendar and select Upload from file.
- Choose the ICS file and select Open.
- Choose the destination calendar and select Import.
The Microsoft import page states that imported events are a snapshot. They do not update when the source changes.
Which Software Moves Calendars Between Platforms?
Method #3: SysTools Migrator (Paid Software)
Who it suits. Admins who move calendars for many users. Extra application. Windows migration software.
The SysTools Migrator moves email, contacts, calendars and Drive data between cloud platforms. The vendor page lists Office 365, Google Workspace, IMAP, Exchange and Lotus Notes as sources and destinations.
The trial migrates email for 2 users.
What About Google Calendar?
Google calendars follow the Google Calendar to Outlook guide. A PST calendar for Google follows the PST to Google Calendar guide.
Where Else does Outlook Data Move?
- Move a full profile with the Outlook profile migration guide.
- Import mail files with the PST import guide.
- Create a backup of the mailbox with the Office 365 mailbox backup guide.
Frequently Asked Questions
How do You Migrate an Outlook Calendar to Office 365?
Export the Outlook calendar to a PST file, then import the file into your Office 365 mailbox in classic Outlook.
Can You Upload an ICS File?
Yes. The web version has Add calendar and Upload from file.
Do ICS Events Update After the Import?
No. Microsoft states that imported events are a snapshot.
Does New Outlook Import PST Calendars?
No. Microsoft states that importing a calendar from a PST file is not supported in new Outlook.
Can You Choose the Destination Calendar?
Yes. The upload dialog asks for the destination calendar.
Can Software Move Calendars for Many Users?
Yes. The SysTools Migrator moves calendars between cloud platforms.
How Many Users does the Trial Move?
The trial migrates email for 2 users.
Author's Verdict
Use a PST file when the Outlook calendar sits in classic Outlook.
Choose the ICS upload for one calendar from any app.
Key Takeaways
- Classic Outlook imports PST calendars.
- ICS uploads copy the events once.
- Software handles many users.
Related Guides
- Export Office 365 Calendar to PST
- Migrate Google Calendar to Outlook
- Migrate Microsoft Outlook to Office 365
Using Thunderbird for calendars? Read how to import an Outlook calendar to Thunderbird.