Instead of trying to figure out how to create a successful formula.

I only did the 5% maintenance because that was the way I saw it on the formulas to calculate but you bring up a good point that it might not always be enough. 

.), search up at the top and there will likely be a blog post that goes over the formula in detail.

I would seek out what fits my formula and pursue it.

If your using it in excel DO NOT use the IRR function as you are much better using XIRR OR IRR in a formula to get it based on monthly cash flows.

If you’re looking to rent and then Airbnb you want Brian Page Airbnb Formula. 

After year one, IRR will be much more accurate and it's also the most straight-forward route to compare different investments - real estate or other - based on yield.One last formula to throw in is your return on equity. 

@Nathan ScottIt's possible to compute the rental vacancy rate for various markets within the country by using data from the American Community SurveyThe formula is as follows:The rule of thumb most investors use when underwriting is 7%. 

The typical formula is that the buyer doesn't want to spend more than 70% of the ARV (After Repair Value) minus the repair costs. 

Facebook even has tools that allows advertisers to test for the effect ads have had on brand recognition.When it comes to advertising for leads, there's a formula that is a good guiding principle: Return on Ad Spend.