So, you want (for many possible reasons) to know the GUID that is associated with a List in your SharePoint. Worry not! It is amazingly simple – once you know the trick.
Go to the List and List Settings. Right click on “Title, description and navigation” (see image below).
Then, paste it into your favorite text editor (Notepad, NotePad++, etc). Cut the whole portion after “List=”. What you just cut is the URL encoded GUID for the list! Now use whatever tool you like to decode the value. If you don’t have a tool, check out http://www.albionresearch.com/misc/urlencode.php
And Whamo! You’ve now got the GUID for you list. Piece of cake!
Hope this is helpful.