Return on Equity Calculator

[Clayton Smith]

Looking to get some advice on when it is time to pull equity out of a house. Trying to find a formula that I can keep an eye on month to month. 

I have some equity in my portfolio but with higher interest rates my payment will increase significantly on some of my rentals. So let's say I can pull out $25k with $2,500 in closing but my payment will go up $500 a month. How do I decide if it is time to do that. Seems like the ROE is to simple for cash out refi because it doesn't take into account the loss of cash flow by increasing the payment. 

Is it as simple as the yearly increased cost divided by the amount I took out to get a return divided by the number of years it would have taken me to accumulate that amount without the refi? 

Any thoughts or advice would be appreciated.