Biweekly Mortgage Calculator
See how much interest you can save by switching to a biweekly mortgage payment schedule. Enter your loan amount, interest rate, original loan term and any extra payment you want to add per biweekly period. The calculator shows your standard monthly payment, your biweekly payment (half the monthly amount), and simulates the loan year by year to calculate how much sooner the loan pays off and how much total interest you save. Because there are 26 biweekly periods per year (but only 24 half-monthly amounts), you effectively make 13 full payments annually instead of 12. That extra payment to principal compounds significantly over time. The calculator also lets you add additional principal beyond the biweekly structure for even faster payoff and bigger savings.
On a $320,000 loan at 6.5% for 30 years, switching to biweekly payments saves approximately -- in interest and pays off the loan -- sooner.
How the biweekly mortgage calculation works
The standard monthly payment uses the PMT (payment) formula described by the CFPB in Understand Loan Options. The biweekly payment is half that monthly amount, plus any extra payment you specify.
r = annual rate / 100 / 12
n = term years x 12
monthly P+I = loan x r x (1 + r)^n / ((1 + r)^n - 1)
biweekly payment = monthly P+I / 2 + extra
Because there are 26 biweekly periods per year but only 24 half-monthly amounts in 12 payments, paying biweekly means you make the equivalent of 13 full monthly payments each year instead of 12. That extra month of principal reduces the balance faster, compounding the interest savings over time.
Simulation method
The calculator simulates the loan year by year. Each year, 26 biweekly payments are applied, with interest accruing monthly on the outstanding balance. The simulation runs until the balance reaches zero, recording the total interest paid. The same is done for the standard monthly schedule, and the difference is the interest saved.
Worked example
$320,000 loan, 6.5% fixed rate, 30-year term, no extra payment:
- Monthly P+I = $2,022.74 (PMT formula)
- Biweekly payment = $2,022.74 / 2 = $1,011.37
- Annual biweekly payments: 26 x $1,011.37 = $26,295.62 (vs 12 x $2,022.74 = $24,272.88)
- Extra per year: $26,295.62 - $24,272.88 = $2,022.74 (one full extra payment to principal)
- Result: approximately 5 years and 4 months cut from the 30-year term and over $60,000 saved in interest
Biweekly vs monthly: which is better for you?
A biweekly schedule works best when your employer pays you every two weeks, making it natural to budget a payment from each paycheck. The discipline of a structured schedule also suits borrowers who prefer automatic savings.
If your lender does not offer a genuine biweekly processing arrangement, consider adding one-twelfth of your monthly payment to each regular payment instead. Over a year, you will make the same extra contribution. Always confirm with your servicer that the additional amount is applied immediately to principal.
Before accelerating your mortgage, weigh it against other priorities. High-interest debt such as credit cards costs more per dollar of balance than your mortgage rate. Contributions to a tax-advantaged retirement account, such as a 401(k) up to the employer match, or an HSA, may also produce a higher after-tax return than the mortgage rate saved. The CFPB's Owning a Home resource provides a broader framework for these decisions.
Watch out for third-party biweekly programs
Some third-party companies charge setup and ongoing fees to manage biweekly payments on your behalf. These fees can erode or eliminate the interest savings. Most lenders allow you to set up a biweekly arrangement directly, or you can replicate the effect by making one extra principal payment per year at no cost.
Biweekly mortgage: frequently asked questions
How does a biweekly mortgage payment work?
Instead of making 12 monthly payments per year, you make 26 half-payments (one every two weeks). Because there are 52 weeks in a year, 26 half-payments equal 13 full monthly payments, not 12. That extra payment goes entirely to principal each year, reducing your balance faster and saving a significant amount of interest over the life of the loan.
Does my lender have to accept biweekly payments?
Not automatically. Many lenders only process payments once a month, which means a biweekly payment sent mid-month may sit in a suspense account until month-end, giving you no interest benefit. Contact your servicer first. If they do not offer a free biweekly program, a simpler approach is to make one extra principal-only payment each year, or to add one-twelfth of your monthly payment to each regular payment. The CFPB's Owning a Home resource at consumerfinance.gov explains your payment options.
Can I just make extra principal payments instead of going biweekly?
Yes, and for many borrowers it is more flexible. Paying one additional monthly payment per year directed to principal produces almost identical savings to a true biweekly schedule. You can also pay a fixed extra amount each month. The key is ensuring the extra amount is applied to principal, not held as a future payment. Ask your servicer to confirm in writing how they apply overpayments.
How much interest can a biweekly schedule save?
On a typical 30-year $320,000 mortgage at 6.5%, switching to a biweekly schedule can save roughly $60,000-$70,000 in total interest and cut around 5-6 years off the loan term. The exact amount depends on your loan balance, rate, and term. Use the calculator above for your specific numbers.
Is a biweekly mortgage right for everyone?
It depends on your cash flow and financial priorities. If you carry higher-interest debt such as credit cards, paying that off first will save more money. Also consider whether your emergency fund is fully funded before committing extra mortgage payments. The CFPB advises reviewing your full financial picture before prepaying a mortgage.
What happens to my escrow if I switch to biweekly payments?
Escrow for property taxes and homeowners insurance is typically collected monthly regardless of how you structure your principal and interest payments. Check with your servicer about how they handle escrow under a biweekly arrangement. Some servicers split the escrow portion across 26 periods; others keep monthly escrow billing separate.
Official sources
- PMT formula and mortgage concepts: CFPB, Owning a Home.
- Loan options explained: CFPB, Understand Loan Options.
Reviewed by the CalculatorHub team, edited by James Graham, 12 June 2026. See our methodology. General information, not financial advice.