How do you determine the rent of a rental property?

[Joshua Bush]

Hello All,

I'm new to real estate investing. At the moment I'm taking an online course and have read 4 of Robert Kiyosaki's books on investing. I'm at the point in online course where we're encouraged to evaluate properties. I live in Maryland and would like to invest in the DMV area. In this area the typical single family home I've seen runs between $200,000 to $400,000. 

My question is: for this property range, how would you calculate the rent you'd receive? For example I'm looking at a $299,995 single family home and the estimated rent for this house is $998/mo. But my understanding was that would only be the principle and interest not the full rental income.