Microsoft produced a basic pricing calculator to help Azure customers. But as you can see here, customer feedback on this calculator was not particularly positive. In the Azure training I do, I find partners too found this old calculator not overly outstanding.
But, MS has listened and has begin rolling out an entirely new Calculator. So far, there's a new calculator for Virtual Machines which you can access at: http://azure.microsoft.com/en-us/pricing/calculator/virtual-machines/. The VM calculator looks like this:
This is a distinct improvement – I look forward to seeing further improvements in the calculator.