Bi-Weekly Mortgage Calculator Enter the principal balance of your mortgage: (call your mortgage lender and ask for the current payoff amount) Enter the amount of your monthly mortgage payment: Enter the your mortgage's current interest rate: Interest you will pay under your current monthly payment plan: Interest you will pay if you switch to a bi-weekly payment plan: Bi-weekly Mortgage Interest Savings: This calculator will show you how much you will save if you make 1/2 of your mortgage payment every two weeks instead of making a full mortgage payment once a month. Note: When entering numbers into the data fields only use numbers and applicable decimal points. Entering commas, dollar signs, or any other non-numeric characters will cause an error. Also please note that this calculator has been tested to work with Internet Explorer 5.5 and Netscape Navigator 4.6 web browsers. However, both must have the JavaScript option turned on.