Mortgage Switching Calculator - Click below for a quick calculation of whether it is worthwhile to refinance your mortgage. The calculator is in British pounds, but our CPA tells us that it should be proportional and still be a rough indicator. You'll need your current interest rate, prepayment penalties, and the time period the penalty applies. If you are in a "5-4-3-2-1", you can do the calculation using the current penalty and the # of years before the penalty ends, i.e. 3% and 3 years remaining. Since the program assumes 3 years at 3%, rather than "3-2-1", you would presumably require a less favorable replacement rate than the program calculates to make refinancing a smart move. Fill in your balance and penalty in dollars where it calls for pounds. If you are mathmatician and know these assumptions to be inaccurate, or if you have a better calculator, please let us know.