How to Determine Positive Cash Flow

[Wes Sitser]

Hello,

I am new to real estate investing. From what I have learned over the last few weeks it seems like a small multi-family will be a great place for me to start.

I learned the 50% rule to quickly weed out bad investments. However, I have found a few multi-family's that look promising, but I do not know where to go from here. 

How do I more accurately calculate whether a property will create a positive cash flow? Are there spreadsheets, formulas, or certain information I need to be searching for?

Any help would be very much appreciated! Thank you very much!