I'm in the middle of trying to refinance and kept getting frustrated that every calculator online basically just tells you your new monthly payment. There's a lot more to the decision than that; tax deductions, opportunity cost of the closing costs, cash-out vs. pay-down, PMI, what happens to your investment portfolio in each scenario. So I built something that models all of it and shows the net worth impact year by year. You can compare multiple scenarios side by side and save your inputs for later. Still a work in progress. Would love feedback if you use it.