We'd use the appraisers opinion of market rent to calculate DSCR and just want to see at least a 1.0 (Rent divided by PITI). 

Any lender should be able to give you a super quick calculation of estimated savings based on those factors to see if this is a good time for you to refi!  

For preliminary numbers analysis, I’m using an online calculator available at this website: https://www.calculator.net/rental-property-calculator.html.

I found that some of their calculations were off when I was looking at certain properties. 

Back of the napkin analysis (or BP calculator) make a conservative offer and see if the seller is willing to play ball.  

When I calculate out the monthly mortgage for a house at this cost assuming a 300,000 downpayment, it would come to around 7450/month so I think 7000/ month is reasonable.  

Basically if the payment amounts would be calculated like they are being paid over a 30/15/10, etc. year term. 

@Mario MoralesCash-on-cash return measures the amount of cash flow relative to the amount of cash invested in a property investment and is calculated on a pre-tax basis.In theory if your rental income increases by X amount annually due to the rehab while holding your expenses constant so it directly increases your bottom line (cash flow), you can calculate the CoC return by inputting X/$45k (the cost).

I roughly calculated 50% of my gains came from appreciation and 50% from cash flow and mortgage payoff.  

I use Zillow and the Rental Property calculator on this site to do all of my LTR analysis.