Microsoft introduced the Microsoft Azure Total Cost of Ownership (TCO) Calculator in preview. This TCO Calculator allows you to evaluate potential cost savings if you migrate on-premises application workloads to Microsoft Azure. You specify the details of your existing infrastructure, various cost assumptions you want the tool to work with, and then you receive a report that shows on-premises costs compared to Microsoft Azure costs.
Find the Microsoft Azure TCO Calculator here: http://tco.microsoft.com/Home/Calculator.