Your Fix and Flip Formula

[Ashley Benning]

I've been doing research and forum stalking for a while now, and am getting ready to take the leap and purchase my first Fix and Flip. (By "ready" I mean "within the next 12 months.") I'm trying to pin down a formula for my flips, something that creates reasonable ROI and that I can use in my decision making. I'm thinking it'll look something like this:

ARV= (purchase price + estimated reno cost) * 1.2

If it doesn't meet that criteria, I won't purchase. But the more I try that formula with sample properties, the more I wonder if that is feasible in my market (Los Angeles suburbs, San Fernando Valley). 

What are YOUR formulas? Or do you do something different to determine if a property is right for you?