How to use Microsoft 365 shared calendars outside your organization

This guide will show you how to create a new shared calendar in Microsoft 365, and then share it with someone outside your organization.


Open your Outlook calendar; under the list of calendars on the left, select New Calendar.


Label the calendar.


Right click on the calendar name and select Sharing & Permissions.


Add the email address of the external person you want to share with. Since you’re sharing your calendar (the room calendar) with a person outside your organization, you will not be able to give them edit permissions.


Select the level of permissions for shared calendar visibility.
Can view when I'm busy allows others outside your organization to see only event times. If you’re comfortable with sharing more information, Can view titles & locations details will show Free/Busy time, titles, & location. 


Repeat these steps for each of your room calendars in Microsoft 365. 
If the person you shared the calendar with uses Microsoft365, Outlook, or another kind of Exchange app they will receive an invitation and be able to add your calendar to their list. 

Cross platform permission issues

These steps on how to use Microsoft 365 shared calendar with external users have a couple limitations for the average organization.

The above process only works for people also on Exchange or Microsoft 365. Google users can view the calendar via a link emailed from Outlook. However, they will not be able to access your shared calendar invitation without a 3rd party app due to different calendar formats. 

Google (and non-Outlook) users will receive an email that looks like this:



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