How will a difference in interest rates change my
monthly mortgage payments? I have created a small
spreadsheet to the right which shows how your mortgage will change depending on your interest rate. However, the more interesting figure is how much you will pay in interest rate charges only– over the course of a 30 year $500,000 loan. At 7% you will pay almost 700K whereas at 5% it will be 466K a difference of almost a quarter million dollars.