It takes a year for biweekly payments to add up to an extra payment.
The first figure on each line below shows the loan's principal balance at the end of that year's monthly payments. Most of us won't live in a single house for thirty years, but don't let that stop you from paying bi-weekly, because shorter term savings are significant. There are intermediary companies that can set up a pseudo biweekly payment plan for you, for a fee. Your principal balance would equal the following amounts at the end of each year shown. No matter how you do it, making one or more extra payments each year significantly reduces the amount of interest you'll pay on your home loan. Many lenders charge a one-time fee to set up a bi-weekly payment plan. The second figure shows how much principal remains at that same time for someone making bi-weekly payments. Just like the accelerated bi-weekly payments, you are in effect paying an additional monthly payment each year. Every dollar of that extra payment goes towards reducing the principal balance of your loan, the balance that future interest calculations are based on.
Your lender won't accept half payments mailed to them twice each month, but they'll likely set up a plan to deduct the payment from your bank account every other week. As you reduce the principal, you reduce the total interest paid and the length of time it takes to pay the loan. The numbers in parentheses represent the balance due at the same point in time for someone on a bi-weekly plan.