May turn primary home of 10 yrs to rental - How to calculate ROI?

[Dan Vollmer]

I came across an interesting opportunity to possibly get me started in real estate investing which I have been trying to get in for some time now.

I am in the process of moving to a new home, and was considering turning my current home into a rental property.  Most calculators seem to be built for new purchases to rent as an investment rather than my predicament.  Are there any calculators, articles, or suggestions that can be provided so I figure out if this is a prudent investment?  Is it as simple as adding interest paid on the mortgage over the last 10 years and property enhancements to the purchase price and treat the rest as normal?

Appreciate in advance the help!