How do I know if the “Numbers” will work?

[Kerry Pangan]

Looking to purchase my first duplex. What numbers do I specifically look for in “Making the numbers work”? I know enough that if a duplex both side rents a couple hundred dollars over the mortgage than you’re in the green.

[Nathan Gesner]

You start with the rent income. Subtract your estimated percentages for maintenance, capital expenditures, vacancy, property management, taxes, and insurance. Subtract the cost of your mortgage (principal and interest). What you have left over is considered "cash flow". Most investors will try to aim for at least $100 cash flow per month, but that depends on your situation, the market, and other factors. Just assume $100+ is a good starting point.

Here's just one of many examples of how to evaluate a property:

(137) How I Quickly Analyze a Rental Property for Cash Flow | BiggerPockets - YouTube