For something more robust, tools like Excel or online calculators from financial planning sites might better suit your needs.Your ROI Formula:ROI = (Net Cash Flow ÷ Total Out-of-Pocket Investment) × 100For your scenario:Net Cash Flow = Annual Rental Income - (Mortgage Payment + 401k Loan Payment + Other Expenses)Total Out-of-Pocket Investment = $40,000 cash + $50,000 loan payments over 5 years.I came across a piece in Bloomberg recently discussing creative financing, and they touched on ROI calculations for multiple loans.Personal anecdote: A buddy of mine leveraged a 401k loan for a fourplex.

I invite my clients to meet with me at quarterly to discuss their investment goals and strategies to grow their portfolios. 

Not many folks on here discussing this approach.How has this method been working in the current RE market?

If the change has occurred and buyers are now doing this, surprised not discussed more  You as the buyer is paying for the agents commission one way or another , either by a higher sales price , or by cutting a check to your agent . 

A handy search bar in the upper right makes it easy to find previous discussions, blogs, podcasts, and other resources.

Great tools that get updated regularly.I am on the lending side of things and would be happy to hop on a call with you anytime to discuss financial strategies and help answer any questions you may have about nearly any loan product available to help you on your journey, even if they are not products my capital partners offer.We are all here to help you learn and grow.

Before you put too much thought into this, I would develop an order of magnitude for this discussion. 

I have gone to numerous RE meetups and discussed numerous ADU appraisals and was heavily involved analyzing one (that gave a value of ~$50k for a ~400’ garage conversion 1/1.  

I am in early discussions with sellers about a seller finance deal near Portland, OR. 

Great tools that get updated regularly.I am on the lending side of things and would be happy to hop on a call with you anytime to discuss financial strategies and help answer any questions you may have about nearly any loan product available to help you on your journey, even if they are not products my capital partners offer.We are all here to help you learn and grow.