It's obvious that if you pay off your mortgage early you will save on interest. But how much? We have a number of calculators that will tell you how much you can save by making extra mortgage payments. This particular calculator is the best to use if you have a date you would like to pay off your mortgage by and know your current mortgage balance. You input the date you want to pay off by and it will tell you what payment you need and the total interest youwill save.