ROI formula used by Biggerpockets.com Calculator

[Marcus House]

For the investor calculator on Biggerpockets.com that I am using to evaluate apartments for buy and hold, when it does its ROI calculation does it include monthly P&I as an expense in calculation of ROI?

Here is what I think it is using:

ROI equals projected annual net income divided by total cost.

My total cost calculation is downpayment plus closing cost plus rehab cost.

Annual net income is projected gross rents for Y1 minus projected expenses for year 1 to include debt service.

Please let me know if this is correct and if not how is the calculator doing this on this site.