Export all calendars from Gmail
- On your computer, open Google Calendar. You can't export your calendar from the Google Calendar app.
- At the top right, click Settings
> settings.
- To download your events, click Import & export.
- Under “Export" click Export. A ZIP file downloads to your computer. If you open the ZIP file, you'll find individual ICS files for each of your calendars
Import Calendar to Office 365
- Login to Office 365
- Browse https://outlook.office.com/calendar/view/month
- Click Add Calendar as shown in the below image
- Click the 'Upload from file' and browse the extracted file as shown below
- Select Calendar and click the Import button.
