Biweekly Mortgage Calculator
Paying half your mortgage payment every two weeks adds up to 13 monthly payments a year instead of 12. Enter your loan, rate and term, add any extra principal, and see how many years and how much interest the biweekly schedule saves, with a full payoff schedule and balance chart.
Formula
Worked example
$300,000 at 6.5% over 30 years: monthly payment is about $1,896, so the biweekly payment is about $948. Paying $948 every two weeks clears the loan in about 24.5 years instead of 30, saving roughly 5.5 years and about $80,000 in interest. Adding $200 extra principal a month shortens it further.
How a biweekly mortgage works
On a biweekly plan you pay half of your normal monthly payment every two weeks. Because a year has 52 weeks, that is 26 half-payments, which equals 13 full monthly payments instead of the 12 you make on a standard monthly schedule. That one extra payment each year is applied entirely to principal, so the balance falls faster and the loan amortizes ahead of schedule. This calculator compares the standard monthly schedule against the biweekly schedule and shows the payoff time for each, the years saved and the interest saved.
Accelerated vs equivalent, and adding extra principal
The biweekly method selector offers two ways to model the speed-up. Accelerated bills you half the monthly payment every fortnight, the true biweekly schedule a lender or service would set up. Equivalent instead keeps a monthly schedule but adds one-twelfth of the payment to each month, which produces almost the identical payoff with no biweekly billing and usually no fee. Either way you can add an extra principal amount per month, which is layered on top of both plans (split in half on the biweekly side) so you can see the combined effect of paying fortnightly and overpaying.
Why it saves interest and time
Mortgage interest is charged on the outstanding balance, so anything that shrinks the balance sooner reduces the interest that accrues afterwards. The extra annual payment under a biweekly plan does exactly that, compounding into a meaningfully shorter term, often four to six years on a 30-year loan, and tens of thousands less in total interest. The amortization schedule and balance chart below trace the falling balance year by year so you can see exactly when the loan clears. The savings come from paying more each year, not from any special compounding of biweekly payments.
Things to check before you switch
Confirm your lender actually applies each biweekly payment to principal when received, rather than holding the half-payments and disbursing them monthly, which would erase the benefit. Watch for biweekly enrollment fees from third-party services, since you can usually achieve the identical result for free by choosing the equivalent 1/12 method or making one additional monthly payment per year. Also make sure there is no prepayment penalty on your loan, and that overpaying still leaves you a healthy emergency fund.
Three ways to pay your mortgage down faster
| Method | How it works | Typical fee |
|---|---|---|
| Accelerated biweekly | Half the monthly payment every 2 weeks (26/yr) | Often a setup fee via a service |
| 1/12 extra each month | Add one-twelfth of the payment to each monthly payment | None, do it yourself |
| One extra payment a year | Make a 13th full payment once a year | None, do it yourself |
| Custom extra principal | Add any fixed amount to each payment | None, do it yourself |
All three reach a similar payoff; the difference is billing mechanics and fees.
Frequently asked questions
Does a biweekly mortgage really save money?
Yes, because you make the equivalent of 13 monthly payments a year instead of 12. The extra payment reduces principal faster, which cuts the interest charged on the remaining balance and shortens the term, typically by several years on a 30-year loan.
Is biweekly the same as paying extra each month?
Almost. Adding one-twelfth of your monthly payment to each monthly payment produces nearly the same result as 26 biweekly half-payments, usually with no enrollment fee. Use the equivalent method in this calculator to compare the two directly. The biweekly schedule mainly helps people who are paid every two weeks.
Can I add extra principal on top of biweekly payments?
Yes. Enter an extra principal amount per month and the calculator layers it on both plans, splitting it in half on the biweekly side. The amortization schedule and chart update to show the faster payoff and the additional interest you save.
Are there downsides to biweekly payments?
Some lenders or third-party services charge setup or transaction fees, and a few hold half-payments until a full monthly amount accumulates, which removes the benefit. Make sure payments are applied to principal immediately and that your loan has no prepayment penalty.