Multiply that by the sqft of the home you're looking at and that will give you a rough ARV idea. 

You basically take the monthly rental income and multiply it time .50 (50%) to estimate expenses for the property in order to establish the Net Operating Income (NOI).  

Some states, like Arizona, do not re-assess upon transfer so you just have to grow the existing assessed value by a multiplier (AZ law limits it to 5% annually).  

The rent multiplier is 3.25 and no maintenance costs.  

I'm hoping this current project will enable me to start multiplying the number of units I have. 

Now take each and multiply by 2 and add 20% for contingency that would be your starting time and money budget. 

If the comp property sold at $1,600,000 and had similar rents then it sold at a 13.75 GRM gross rent multiplier. 

Then I multiplied the original square footage of each duplex by the equation to get the expected cost of each duplex in my spreadsheet.

Net cash flow = 100K** (This assumes a conservative 3x multiplier)Debt service payment (150K, 6% rate, 5 year amortization) = 35,600Cash flow = 100,000-35,600= 64,400/yearROI = 64,400/150,000 = 43%After 5 years, debt is paid and income = 100K.

If you can get an average of price-per-square foot for properties within a quarter mile of yours, just multiply that by your square footage and you'll have a pretty decent estimate of the property's current value.Depending on how much equity you have, you could sell it and get all of it, keep it and have the renter pay the mortgage off over time, or pull out some equity to invest in other properties.