Paying your mortgage every two weeks sounds like a small scheduling change, but it quietly adds a 13th payment every year. That extra money goes straight to principal, so the balance falls faster and interest shrinks for the rest of the loan. This bi-weekly mortgage calculator puts a standard monthly schedule next to a bi-weekly one. You see the interest saved, the new payoff date and the balance year by year. It also lets you net out any fees a bi-weekly program charges.
How to use the bi-weekly mortgage calculator
- Enter the loan amount, interest rate and loan term.
- Choose how the payments are applied:
- True bi-weekly: half the monthly payment every 14 days, with interest charged every two weeks.
- Monthly + 1/12 extra: what many servicers and do-it-yourself plans actually do. Your monthly payment plus one-twelfth extra, applied once a month.
- Enter any setup fee or fee per payment charged by a bi-weekly service.
How bi-weekly payments work
The bi-weekly payment is half the regular monthly payment:
where M = P · r(1 + r)n ÷ [(1 + r)n − 1] is the standard monthly payment. With true bi-weekly payments, interest is charged at the annual rate ÷ 26 each period. Paying a little sooner trims interest slightly, and the extra half-payments cut the balance by about one monthly payment each year.
Worked example
A $320,000, 30-year loan at 6.5% has a monthly payment of $2,022.62 and costs $408,142 in interest over its full term.
- Bi-weekly payment: $2,022.62 ÷ 2 = $1,011.31 every two weeks, or $26,294 a year versus $24,271.
- Payoff: 24 years, 2 months (628 payments). That is 5 years and 10 months sooner.
- Total interest: $314,146, which saves $93,997.
- The “monthly + 1/12” method ($2,191.17 a month) gets almost the same result: $93,073 saved and the same payoff time.
Savings by loan term
$320,000 at 6.5%, true bi-weekly:
| Term | Monthly payment | Time saved | Interest saved |
|---|---|---|---|
| 30 years | $2,022.62 | 5 years, 10 months | $93,997 |
| 15 years | $2,787.54 | 1 year, 10 months | $25,456 |
The longer the loan and the higher the rate, the more an extra payment a year is worth.
Before you sign up for a bi-weekly plan
- Ask your servicer how it handles partial payments. Some hold a half-payment in a suspense account until the other half arrives. In that case you only benefit from the extra payment once a year.
- Watch for fees. A $395 setup fee plus $2.50 per payment would cost $1,965 over this loan. You can skip the fees by setting up an automatic extra principal payment yourself.
- Match it to your paycheck. Bi-weekly payments are easiest for people paid every two weeks. In two months each year you get three paychecks, which covers the extra payment.
- Keep flexibility. A voluntary extra payment can be stopped in a tight month. A contractual bi-weekly plan may not be as easy to pause.
For other ways to pay down early, such as lump sums or a different extra amount, use the mortgage payoff calculator. If rates have dropped, compare paying faster with a new loan in the refinance calculator.
Estimates only. Your servicer's posting rules, day-count method and any prepayment terms determine the actual savings.
Frequently asked questions
How much does a bi-weekly mortgage save?
On a $320,000, 30-year loan at 6.5%, paying $1,011.31 every two weeks instead of $2,022.62 a month saves about $94,000 in interest. It also pays the loan off in about 24 years and 2 months instead of 30 years. The savings come from making the equivalent of one extra monthly payment each year.
Why do bi-weekly payments add up to an extra payment?
A year has 52 weeks, so paying every two weeks means 26 half-payments, or 13 full monthly payments instead of 12. The 13th payment goes entirely to principal, which reduces the interest charged on every payment after it.
Is a bi-weekly program worth paying a fee for?
Usually not. Many third-party programs collect your half-payments and send them to the lender monthly, sometimes for a setup fee and per-payment charges. You can get almost the same savings for free by adding one-twelfth of a payment to principal each month, or one extra payment a year. Check first that your servicer applies extra money to principal.
Does bi-weekly work on a 15-year mortgage?
Yes, but the savings are smaller because there is less interest to cut. A $320,000, 15-year loan at 6.5% pays off about 1 year and 10 months early and saves roughly $25,000 with bi-weekly payments.