Biweekly Mortgage Payment Calculator

Switching from twelve monthly mortgage payments to twenty-six biweekly half-payments is one of the simplest ways to pay off a home loan early. Because there are 52 weeks in a year, paying half your monthly payment every two weeks results in 26 half-payments — the equivalent of 13 full monthly payments instead of 12. That one extra payment per year goes entirely toward principal, which shrinks the balance faster, reduces the interest that accrues on it, and compounds into years of saved payments over the life of the loan. This calculator takes your loan amount, interest rate, and term, computes the standard monthly payment, and then simulates the biweekly schedule to show your new payoff date, the total interest under each plan, and the money and time you save. The effect is largest on new, long, high-rate loans: on a typical 30-year mortgage the biweekly schedule trims roughly four to six years off the term and saves tens of thousands of dollars in interest — without ever feeling like a bigger payment, since each individual payment is half the usual size. Before enrolling in a lender's biweekly program, check for fees: you can usually replicate the identical result for free by adding one-twelfth of your monthly payment to each regular payment as an extra principal contribution.

The standard monthly payment is calculated with the amortization formula M = P × [r(1+r)^n] ÷ [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments. A biweekly schedule pays half of M every two weeks. Since a year contains 26 two-week periods, you make 26 half-payments — 13 full payments' worth — instead of 12. The calculator models this as the standard monthly payment plus one-twelfth extra applied to principal each month, which is mathematically equivalent over a year and matches how most lenders credit biweekly programs. The simulation accrues interest on the remaining balance each month, applies the accelerated payment, and counts months until the balance reaches zero. Interest saved is the difference between total interest under the two schedules. Actual savings vary slightly with how your lender credits mid-cycle payments — some credit each biweekly payment immediately (saving marginally more), while others hold the half-payment until the full amount arrives.