After you estimate your gross monthly revenues (be conservative here), you need to start subtracting stuff - PITI/CapEx/Operating expenses/Etc.

If you look at your bank account balance when the project is done and subtract the bank account balance when the project started, in theory, the result should be your pre-tax profit.

I apologize I'm screwing myself in my head right now on the math or how the bank views it.Say if you have a vacant lot (you own) that already has design and basically is shovel ready (has permits)Total project is $2 millionLand and equity you already own is $500kConstruction costs is $1.5 million.So in this scenario all you need is a $1.5 million dollar loan for construction.Since the bank is using equity at 25% does that now mean that the $500k will be subtracted from the $1.5 million since that is all you need?

At face value, my DTI ratio is too high, as the lender will likely do one of two things: A) Use previous tax returns showing I'm collecting $1650/mo in rent, and subtract that from my monthly obligation ($2300) leaving me with a net loss on the first condo of $750 ($2300-1650)B) Take 75% of expected rental value (let's say 75% x 2400 = 1800), and count the difference of 1800 and 2300 as a net debt against me for the first condo.

Subtract your $1640 piti payment, subtract $220 for management fees, subtract 5% for vacancy, 5% for repairs and 5% for CAPEX.

It is a value subtract.  

Calculating your rates of return without subtracting the inflation rates gives a very skewed look at your investments. 

The value when you inherited was your basis, then you subtracted depreciation.

You can write these losses off for a second home that you partially use yourself (although technically you should subtract a % for personal use no one is going to be checking or have any way to know if you stayed there).

It's when I subtract 15% rent hold back for vacancy/capX/repairs and PM that there's no $ left.