Use our Biweekly Calculator to see how much interest you could save with a biweekly mortgage program. With a biweekly, 30 year mortgage program, you would pay half payments every two weeks. This is 26 half payments per year rather than the typical 12 monthly payments. These 26 half payments equal 13 months of payments and the extra money gets applied to the loan's outstanding balance and can take about 7.5 years off the standard 30-year loan. This type of loan program can also take off up to 30% of the loan's interest costs.