1. In your Google Admin console (at admin.google.com)...
2. Go to Apps > G Suite > Calendar.
3. Click Sharing settings.

4. If you have multiple organizational units, select the one you want to set sharing for.

5. In the External Sharing options section, choose how your users can share their calendars with people outside your organization.
   • Only free/busy information (hide event details)—Users can let people outside your organization know when they're busy or available. But event details are hidden. Private addresses are hidden from users' calendars.
   • Share all information, but outsiders cannot change calendar—Users can share their calendar information with people outside your organization. This includes guest list, location, and description. Private addresses are hidden from users' calendars.
   • Share all information, and outsiders can change calendars—Users can fully share their calendar information with people outside your organization. This includes guest list, location, and description. Private addresses are shown.
   • Share all information, and allow managing of calendar—Users can fully share their calendar information with people outside your organization. They can also grant outsiders permission to manage their calendars. Private addresses are shown.

   If you lower the external sharing level, people outside your organization may lose access to calendars they could previously see.

6. In the Internal sharing options section, choose how your users can share their calendars with other people in your organization. Users can change the settings for their own calendars.
   • No sharing—Calendars aren't shared unless users share their own calendars.
     Note: If you choose No sharing, your mobile app users can't use the Find a time feature.
   • Only free/busy information (hide event details)—Only free/busy information displays.
   • Share all information—All information is public unless users change their own settings. Users can also make individual events private.

   If you change the internal sharing level, the change applies to new calendars and to existing calendars if the user hasn't customized their own calendar settings.

7. In the Video Calls section, select whether you want to Automatically add video calls to events created by a user. If you select this option, users can still remove video calls from individual events.
8. In the External invitations section, select whether you want to Warn users when inviting external guests. Learn more
9. (Optional) To set external calendar sharing options for secondary calendars users create, go to G Suite > Calendar > General.

   You'll see the same options as for primary calendars. You just can't set them for individual organizational units.

It can take up to 24 hours for your changes to take effect.

To update existing calendars:

1. Use the Directory API to retrieve and parse the list of all your users.
2. Use the Google Calendar API to update the Access Control Lists for the calendars.