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Categories: Business;Office 365;SharePoint

​Calendars are very popular in SharePoint. They get added to many sites and subsites in various SharePoint portals, especially to team and project sites.

Although calendars are widely used in SharePoint, not many site owners spend time planning how to use them. I often see subsites with a single calendar crammed with many appointments of different kinds. My usual recommendation is to use one calendar for each type of appointment, but when suggesting this improvement, many site owners are afraid it may affect usability. This is where calendar overlays come into play.


What are calendar overlays in SharePoint?

In a nutshell, with calendar overlays, you can merge multiple calendar views. Those additional views can come from different calendars or from just one calendar. Each overlaid calendar can be displayed in a different color.


How can overlaid calendars be used in SharePoint?

I see two typical use cases for calendar overlays in SharePoint. The first one is to aggregate appointments from multiple calendars into a single view. Here is an example: a marketing team uses one calendar for vacations, another for stat holidays and a third calendar for managing events. With overlaid calendars, the event planning will become much easier as holidays and vacations are superimposed on the events calendar, even though they are managed in different calendars.

The second use case is the popular color coding with different types of events being displayed using different colors. This can be achieved by creating a view for each type of appointment, even if only one calendar is used. Overlaying these views will result in a single calendar view displaying different types of appointments in different colors.


How are calendar overlays created?

Let me show you this by using an example you can recreate in your environment easily. In my demo, I have a subsite with three calendars, a primary calendar, a calendar listing stat holidays and a calendar for vacation requests. I would like to superimpose the calendar with the stat holidays and the vacation calendar on the main calendar. Both calendars are providing a calendar view called 'All Items'. Before I continue with some screenshots, I should mention that calendar overlays only work with calendar views. List views cannot be overlaid.

In my example, I have added Easter Sunday to the stat holidays calendar and a vacation request to the vacation calendar. To create the overlays, I turn to the primary calendar, open the ribbon and select 'Calendar Overlays'


The following dialogue shows up, and I click on the ‘New Calendar’ link:


I create a new calendar overlay for vacations as shown in the next screenshot (don’t forget to click on ‘Resolve’ to be able to select an additional calendar list):


I repeat this step with the stat holidays calendar. After I have done that, the list of overlaid calendars looks like this:


Let's switch back to the primary calendar and see what the overlaid calendars look like:


Here you can see that the view from the vacation calendar (red) is added to the primary calendar and the view from the stat holiday calendar shows up in green. Keep in mind that both appointments are NOT part of the primary calendar. They are still managed in their own calendars.

On the left side, SharePoint shows a legend explaining which calendar is displayed and in what color. To navigate to one of the overlaid calendars, click on the calendar name in the left navigation.

As you can see, it just takes a little additional configuration, to create calendar overlays which improve usability and maintainability. That's why calendar overlays are my hidden gems in SharePoint.