Bi-Weekly Mortgage Calculator 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. In effect, you will be making one extra mortgage payment per year--without hardly noticing the additional cash outflow. But, as your about to discover, you will certainly notice the increased cash flow that will occur when you pay your mortgage off way ahead of schedule! 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: This is how much interest you will pay under your current monthly payment plan: This is how much interest you will pay if you switch to a bi-weekly mortgage payment plan: Bi-weekly Mortgage Interest Savings: Close Window