Why do you need special software to calculate those formulas? 

The cap rate formula calls for NOI divided by "Purchase Price" but note that sometimes people use "Cost" or "Value" in place of "Purchase Price".

thanks

I know that the equity is the most important factor, but if the ROI is great, and the purpose of the Sub 2 is a long term buy and hold strategy shouldn't that make the formula more flexible, since the equity would build faster with a higher ROI?  

Use the NPER formula in excel.

If you were to apply income based valuation on 1 to 4 unit properties, you would likely get the wild swing that you have observed.Second, the formula of "Net Return" as you defined it (i.e never seen it used before) is essentially Cap Rate * 5 (i.e. using your assumption of 20% down).

Should I stick to the ARV formula of 70% on the dollar, and then reduce it further by the rehab costs?

Should I stick to the ARV formula of 70% on the dollar, and then reduce it further by the rehab costs?

(See Ashish example if you want to understand the formula.)3.

NYC uses a magic formula (statistical analysis) to figure out how much your property is worth based on comparing size, style, and age of your unit with your neighborhood.