Paying half your mortgage every two weeks sneaks in one extra full payment a year — and it can knock years off your loan and save a fortune in interest. See your biweekly payment, the time you'd save, and the exact interest difference versus standard monthly payments.
26 half-payments a year
The trick hiding inside a biweekly mortgage is a calendar quirk. If you pay half your monthly mortgage every two weeks, you make 26 half-payments a year — which equals 13 full monthly payments instead of 12. That one extra payment slips in almost painlessly, but because it goes entirely toward principal, it attacks the part of your loan that's generating interest. On a typical 30-year mortgage, that single bonus payment each year can shorten the loan by roughly four to six years and save tens of thousands of dollars in interest. This calculator runs both schedules and shows you the gap.
Why does such a small change do so much? Mortgages are front-loaded with interest — in the early years, most of your payment covers interest and only a sliver touches principal. Every extra dollar of principal you pay early permanently removes the interest that dollar would have generated for the rest of the loan. By chipping in an extra payment annually and paying slightly more often, you accelerate the balance downward, which compounds into large savings over decades. The effect is strongest on long terms and higher rates, which is exactly when interest is the most punishing.
A couple of practical cautions. First, check that your lender applies biweekly payments to principal immediately rather than holding them until a full monthly payment accumulates — if they just hold the money, you lose most of the benefit. Second, beware third-party "biweekly enrollment" services that charge setup and per-payment fees for something you can usually do yourself for free. The simplest do-it-yourself version is to keep paying monthly but add one-twelfth of a payment to each month, or make one extra payment a year — you capture nearly the same savings with zero fees and full flexibility to skip it in a tight month.
26 biweekly half-payments equal 13 monthly payments a year. That extra one goes straight to principal.
On a 30-year mortgage, biweekly payments typically cut 4–6 years and save tens of thousands in interest.
You can replicate the benefit for free by adding 1/12 of a payment monthly. Avoid paid enrollment services.
A biweekly mortgage plan splits the monthly payment in half and collects it every two weeks. Because a year contains 26 fortnights rather than 24, this quietly produces 13 monthly payments a year instead of 12. That thirteenth payment is the entire mechanism — it is not the biweekly frequency that saves money but the extra annual principal. The saving is real and substantial, but you can capture it for free by dividing your monthly payment by twelve and adding that to each payment, rather than paying a servicer a setup fee to do the same thing.
Biweekly payment = Monthly payment ÷ 2Annual total = Biweekly × 26 = Monthly × 13Extra principal per year = one full monthly paymentEquivalent DIY: add (Monthly ÷ 12) to each monthly paymentwhere:
Assumptions: Only works if the servicer applies each half-payment on receipt. Many hold the funds and apply them monthly, which removes most of the benefit — and some charge an enrolment fee for a service you can replicate yourself at no cost.
Compare a standard monthly schedule with a true biweekly one on the same loan.
ResultPaid off ~5.8 years early — about $101,394 of interest saved
The DIY equivalent is adding $2,212.24 ÷ 12 = $184.35 to each monthly payment, which produces the same result with no enrolment fee and no dependence on how the servicer applies funds. Confirm your loan has no prepayment penalty first, though these are rare on US mortgages.