Biweekly mortgage payments

You pay half your scheduled monthly amount every two weeks. Twenty-six biweekly halves equal thirteen full monthly payments per year — one more than the twelve you'd make on a monthly schedule. That extra payment goes entirely to principal, which compounds into faster payoff and less lifetime interest. On a 30-year loan, the typical effect is 4–6 years off the term.

Our calculator models biweekly the way servicers actually apply it. Interest accrues monthly — as nearly every US servicer computes it — and the 26 half-payments cover 12 monthly payments plus one extra full payment a year against principal. A few lenders, mostly credit unions, accrue interest every fourteen days instead, which pays off marginally faster than we show.

You can approximate the same payoff effect two ways:

• Monthly extra: add an extra principal payment each month equal to (1/12) of your scheduled monthly payment. Twelve of those equal one full extra payment per year — the biweekly result.
• Annual extra: add a one-time extra equal to one full scheduled monthly payment, applied once a year.

The biweekly mortgage calculator now models this directly, including the comparison against paying the extra yourself.

• Servicer-run biweekly program. Some servicers offer a built-in biweekly option, often free. Confirm that the extra half-month per year is actually applied to principal — not held as a future scheduled payment.
• Third-party biweekly services. Charge a setup fee plus per- payment fees. They often forward to the servicer monthly anyway, with the "extra" held back as a 13th annual payment. The math you get is usually identical to just paying the 13th yourself — for free.
• DIY equivalent. Pay your scheduled monthly amount plus 1/12 of that amount as extra principal each month. Identical math, no fees, no third-party dependency.

On a $320,000 loan at 6.5% over 30 years, the scheduled monthly payment is about $2,022, so a biweekly payment is about $1,011. A monthly extra of about $169 (which is 2,022 / 12) approximates the same effect.

Running both through our amortization engine, against a plain monthly schedule:

• Biweekly through a servicer: paid off 5 years 9 months early, saving about $91,481 in interest.
• Paying the 1/12 extra yourself: paid off 5 years 10 months early, saving about $93,072 — roughly $1,591 better, because the money reaches principal every month instead of waiting for a full payment to accumulate.

Figures assume interest accrues monthly, which is how nearly all US servicers compute it. A lender doing true 14-day accrual would pay off marginally faster still.

• Don't pay a third party for what you can do yourself. The math is the same; the fees aren't.
• Confirm in your statement that the extra is applied to principal. If it's being held as a future payment, call the servicer and have it re-applied.
• Don't prioritize biweekly extras over building an emergency fund or capturing employer retirement matches.