SharePoint makes it very easy to export Calendars from SharePoint to Outlook.  But what if you have an Outlook calendar that you want on SharePoint?  This becomes more difficult and you could quickly find yourself lost on how to complete this task.  Don’t worry though, it’s not that hard.  The following article will explain a common method of moving pre-existing Microsoft Outlook calendars to a new SharePoint calendar list. 

For Outlook 2007 Users:

1. Create the new calendar in sharepoint, and link it to your Outlook
2. Open the source Outlook calendar (either from exchange or as a PST, however you have it).
3. Go to folder view and open the source calendar
4. With the source calendar open, go to view menu, current view, and select all appointments.
5. Hit CTRL-A to select all the appointments, or just get the ones you want.
6. Drag-and-drop the selected calendar Items to the linked sharepoint calendar
7. DONE.

For Outlook 2003 Users:

1. Create a new calendar list on your SharePoint site.  You can do this by clicking Site Actions > View all Site Content  then…
   
   click Create And select Calendar
   
   
2. Now that our blank calendar is created we can now work on getting the items imported… which is the objective of this article: Open your Microsoft Outlook Calendar and copy the Public Folder by (a.) right-clicking on the Calendar Icon and (b.) copying it into a new folder called “Calendar Copy” located in your mailbox folders (you will have to create this folder before copying). 
   Above: Depending on how old the Calendar and its size it could take 2-20 minutes to copy. 
3. Now in a nutshell it’s time to export your Outlook Calendar into a Excel file format with the following columns:
   • Subject
   • Location
   • Start Date
   • Start Time
   • End Date
   • End Time
   • All Day event
4. We can do this by selecting the “Calendar copy” folder that we just created and clicking File > Import and Export…
   
   
   
   This will bring up the Wizard view 1.  Select Export to a file
   Now select Microsoft Excel 97-2003
   Select the location you wish to save the file.
   This will bring up the date range configuration popup.  
   Select the appropriate dates.
   
   
   Confirm the actions and finish the Wizard.
   If you need more help please check out the following Microsoft Help about Microsoft Outlook Import and Export.
5. Now that your data is in the Excel file let’s open it up and see what’s in there.  At this point you will notice the Start Date and End Date are in two separate columns.   Now before we do anything to this data we will need to go back to the blank Calendar list in SharePoint and switch to All Event View.  You can do this by entering the list and clicking Modify View > All Events View
6. Export this empty view to a Excel Spreadsheet and open it.  You can do this by clicking Actions > Export to Spreadsheet
   
   
   
7. Open this exported Outlook Calendar, merge Start Day and Start Time to a single column.  I’m not going to get into the detailed specifics of how to merge these columns as it may differ for individual users, but… In a high-level overview how to merge the columns you can use a formula similar to:
   
   =CONCATENATE(B:B,” “,C:C) or =CONCATENATE(D:D,” “,E:E) for a blank column in the same workbook to merge 2 column’s data. 
   
   The “B:B” is the column containing the Start date, the ” ” adds a space, and the “C:C” is the End Date.  If your data is in another you must column change the letters correspond to the appropriate column. 
   Above: In the image above you can see column M and N hold both Start/End date and times.
8. Merge End Date and End Time to another single column. Both of these two column should have two spaces between date and time and YY as year, not YYYY or 4 digits.
9. Copy all Subjects from the exported Calendar to Title column of the Calendar list. The rest are straight forward. Do not put anything to WorkSpace column since it’s read-only.
10. Correct any errors if you have any and please post them within this article’s comment for a solution. Then sync this list to the SharePoint calendar.

Final Result:

All items from Outlook are now on our new Calendar.