Work with multiple Exchange and SharePoint calendars in one SharePoint calendar

A SharePoint calendar enables you to work with multiple Exchange and SharePoint calendars at the same time. For example, a group calendar is helpful when you schedule a team meeting, because you can see the Exchange calendars of team members and SharePoint calendars of resources, such as conference rooms, in one group calendar view.

Add multiple SharePoint and Exchange calendars to a SharePoint calendar

Use the following procedure to create a view of multiple SharePoint and Exchange calendars for a SharePoint calendar. A view for a calendar can display a maximum of ten calendars.
Note To change calendar settings, you must have at least the design permission level for the site.

1. In a SharePoint calendar, in the ribbon, on the Calendar tab, click Calendar Overlays.
2. In the Calendar Overlay Settings page, click New Calendar.

• To add a SharePoint calendar

1. In the Name and Type section, type the Calendar Name and then select SharePoint.
2. In the Calendar Overlay Settings section, type a Description for the calendar (optional), and change the Color theme for the calendar (optional).

Tip Selecting different colors for different calendars makes it easier to distinguish which calendar an event is from.

3. Type the Web URL for the SharePoint site that the calendar is in, such as https://contoso.com/TWGroupWorkSite/calendar, and then click Resolve. If the calendar is in the same site as the group calendar, Web URL will already be populated accurately.
4. Click the List drop-down arrow and select the calendar that you want to add to the calendar.
5. Click the List View drop-down arrow and select the view that you want to use for the calendar.
6. If you want this SharePoint calendar to always display in the SharePoint group calendar, select Always Show.

• To add an Exchange calendar

1. In the Name and Type section, type the Calendar Name and select Exchange.
2. In the Calendar Overlay Settings section, type a Description for the calendar (optional), and change the default Color theme for the calendar (optional).

Tip Selecting different colors for different calendars makes it easier to distinguish which calendar an event is from.

3. Click Find. Outlook Web Access URL and Exchange Web Service URL will be filled in automatically. If Find does not work in your environment, type the URLs manually
4. If you want this Exchange calendar to always display with the SharePoint group calendar, select Always Show.

3. Click OK and then click OK again.

Following is an example of the day view of the Team group calendar, overlaying Aamir and Connie’s calendars.

Reference: http://office.microsoft.com/en-us/sharepoint-foundation-help/work-with-multiple-exchange-and-sharepoint-calendars-in-one-sharepoint-calendar-HA101777171.aspx?CTT=1