the 3 most frequently used ratio are, debt coverage, CAP rate, and cash on cash.
1. when I look at a property, I always use zero down, NOI/(interest to bank + interest to me)>=1.1
2. CAP, of course, I need to see 10% CAP.
3. CASH on CASH, 15% or more.
NPV, IRR, easy to do on paper, but in reality, hardly can be followed. RE as a small business, has too many unforeseen variables, any unexpected repair can wipe out the whole cash reserve.
