Biweekly Mortgage Calculator
A biweekly mortgage calculator reveals the quiet power of paying half your mortgage every two weeks. Because a year has 52 weeks, paying every fortnight produces 26 half-payments — the equivalent of 13 full monthly payments rather than 12. That single extra payment each year, applied entirely to principal, can shave years off the loan and save a substantial sum in interest, all without a noticeable change to your routine budget.
- Interest you still pay
- Interest saved
- Biweekly payment
- $790.09
- Time saved
- 5 yr 10 mo
- Interest saved
- $72,713.57
- New payoff term
- 24 yr 2 mo
A biweekly schedule means 26 half-payments a year — the equivalent of 13 monthly payments instead of 12. That one extra payment a year, spread across the months, clears the loan 5 years and 10 months early and saves about 72,714 in interest.
Amortization schedule
| Year | Payment | Interest | Principal | Balance |
|---|---|---|---|---|
| 1 | $20,542.21 | $16,119.79 | $4,422.42 | $245,577.58 |
| 2 | $20,542.21 | $15,823.61 | $4,718.60 | $240,858.98 |
| 3 | $20,542.21 | $15,507.60 | $5,034.61 | $235,824.37 |
| 4 | $20,542.21 | $15,170.42 | $5,371.79 | $230,452.58 |
| 5 | $20,542.21 | $14,810.66 | $5,731.55 | $224,721.04 |
| 6 | $20,542.21 | $14,426.81 | $6,115.40 | $218,605.64 |
| 7 | $20,542.21 | $14,017.25 | $6,524.96 | $212,080.68 |
| 8 | $20,542.21 | $13,580.26 | $6,961.95 | $205,118.73 |
| 9 | $20,542.21 | $13,114.01 | $7,428.20 | $197,690.53 |
| 10 | $20,542.21 | $12,616.53 | $7,925.68 | $189,764.85 |
| 11 | $20,542.21 | $12,085.73 | $8,456.48 | $181,308.37 |
| 12 | $20,542.21 | $11,519.38 | $9,022.83 | $172,285.54 |
| 13 | $20,542.21 | $10,915.11 | $9,627.10 | $162,658.44 |
| 14 | $20,542.21 | $10,270.36 | $10,271.85 | $152,386.59 |
| 15 | $20,542.21 | $9,582.44 | $10,959.77 | $141,426.82 |
| 16 | $20,542.21 | $8,848.44 | $11,693.77 | $129,733.06 |
| 17 | $20,542.21 | $8,065.29 | $12,476.92 | $117,256.14 |
| 18 | $20,542.21 | $7,229.69 | $13,312.52 | $103,943.61 |
| 19 | $20,542.21 | $6,338.12 | $14,204.09 | $89,739.53 |
| 20 | $20,542.21 | $5,386.85 | $15,155.36 | $74,584.17 |
| 21 | $20,542.21 | $4,371.87 | $16,170.34 | $58,413.82 |
| 22 | $20,542.21 | $3,288.91 | $17,253.30 | $41,160.52 |
| 23 | $20,542.21 | $2,133.42 | $18,408.79 | $22,751.74 |
| 24 | $20,542.21 | $900.55 | $19,641.66 | $3,110.08 |
| 25 | $3,134.59 | $24.51 | $3,110.08 | $0.00 |
How it works
There are 12 months in a year but 26 two-week periods. If you pay half your monthly mortgage every fortnight, you make 26 half-payments, which add up to 13 full payments a year instead of 12. That thirteenth payment is pure extra principal.
This calculator models the effect by spreading that one extra annual payment evenly across the year — adding one-twelfth of your monthly payment to each month — then building the full accelerated amortization schedule. Because the extra reduces principal, the balance interest is charged on falls faster, and the saving compounds over the remaining life of the loan.
The headline figure is the interest you avoid versus a plain monthly schedule, alongside how many months earlier the loan is fully paid. The biweekly payment itself is simply half your normal monthly amount.
The monthly payment is EMI = P · i · (1 + i)^n / ((1 + i)^n − 1). Paying half that amount every two weeks means 26 half-payments = 13 full payments a year, one more than the 12 in a monthly plan. The calculator models that extra payment as monthly payment ÷ 12 added to each month, then compares the resulting amortization schedule against the standard monthly one to find the time and interest saved.
Worked example
Take a 250,000 loan at 6.5% over 30 years. The monthly payment is about 1,580, so the biweekly payment is roughly 790 every two weeks. Those 26 half-payments equal one extra full payment a year. The result: the loan is paid off in about 290 months instead of 360 — around 70 months, nearly 6 years, early — and you save about 72,714 in interest compared with the standard monthly schedule.
Things to watch out for
Some lenders charge a fee to set up a true biweekly plan, or hold your half-payments and only apply them monthly, which erases the benefit. You can replicate the effect yourself for free by simply adding one-twelfth of your payment to each monthly installment, or by making one extra full payment a year. Confirm extra amounts go to principal and that there is no prepayment penalty. This model assumes a level interest rate for the life of the loan.
Frequently asked questions
Why does paying biweekly save money?+
Twenty-six half-payments a year equal 13 full monthly payments instead of 12. That extra payment goes entirely to principal, lowering the balance interest is charged on for the rest of the loan, so the savings compound over time.
Is biweekly the same as just paying extra each month?+
Effectively yes. Adding one-twelfth of your payment to each monthly installment produces almost the same result as a biweekly plan, without any setup fee. The biweekly label is mostly a convenient way to enforce that one extra payment a year.
Do all lenders offer biweekly payments?+
Not all, and some charge to enroll or apply the half-payments only once a month, which removes the advantage. Before signing up, check there is no fee and that payments hit your principal on schedule — otherwise just do it yourself.
Will biweekly payments hurt my monthly budget?+
Each payment is only half your monthly amount, so individual payments feel smaller. Over a year you pay the equivalent of one extra monthly payment, so budget for that modest additional outlay.
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Disclaimer: This calculator is for educational and informational purposes only and provides estimates, not financial advice. Interest rates, taxes, fees, and local rules vary and change over time. Confirm figures with a qualified professional before making any financial decision.
Last reviewed: 2026-06-22