Open Outlook
Go to the Calendar view
Select the calendars you want to combine
Use the overlay view to display calendars together
Click the arrow on each calendar tab to overlay them
View all selected calendars in one combined calendar
To merge calendar data, export each calendar if needed
Import the calendar files into the target Outlook calendar
In Outlook on the web, open Calendar
Add or subscribe to the calendars you want to combine
Use the calendar list to show multiple calendars at once
Drag events between calendars if needed
Save changes after combining or importing calendars