Skip to content

Extra and Biweekly Mortgage Payoff Calculator

See how much interest you save and how many years you cut off your mortgage by adding extra to each payment or switching to a biweekly schedule.

Paying extra principal or paying half your mortgage every two weeks shortens the loan and cuts total interest, because interest is charged on the balance you still owe. A biweekly schedule makes 26 half-payments a year, which equals one extra monthly payment. This calculator compares your standard schedule with the faster one and shows the interest saved and the years cut off.

$

The current amount you still owe on the mortgage.

%

The annual interest rate on the loan.

years

Years left on the standard schedule. The comparison is measured against this term.

$

Extra principal added to each payment. Set to 0 to see the biweekly effect on its own.

Biweekly pays half the monthly amount every two weeks, totaling one extra monthly payment a year.

Share
Xfin

Interest saved

$91,173.87

How much less interest you pay versus the standard monthly schedule with no extra.

Time saved
81 months
Time to payoff
279 months
Payment each period
$1,998.65
Total interest (faster schedule)
$256,341.57
Total interest (standard schedule)
$347,515.44
Standard monthly payment
$1,798.65
Total paid
$556,341.57
Balance over time: standard vs faster payoff

Assumptions

  • The standard payment is the normal principal and interest for the loan balance, rate, and remaining term, computed with the standard amortization formula. The extra-payment and biweekly schedules are then simulated one period at a time: each period charges interest on the current balance (rounded to the cent, the lender convention) and applies the rest of the payment to principal, so the balance ends at exactly zero.
  • With no extra and a monthly schedule, the result reproduces the standard payoff exactly (same months, same total interest); the saved interest and time are zero. Any saving comes only from the extra principal or the biweekly cadence you choose.
  • Biweekly means paying half the monthly payment every two weeks, which is 26 payments a year (about 13 monthly payments instead of 12), with interest accruing at the annual rate divided by 26 each period. The extra payment, if any, is added to each payment, so in biweekly mode it is added to every half-payment.
  • Time to payoff for a biweekly schedule is reported in calendar months by converting the number of biweekly periods at 26 periods per 12 months. Interest saved and time saved are always measured against the standard monthly schedule with no extra.
  • The comparison chart pairs the faster schedule's year-end balance with the standard schedule's year-end balance from the same amortization routine. For a biweekly schedule each set of 26 payments is treated as one year on the chart.
  • All figures are nominal dollars and are not adjusted for inflation or taxes. Escrow items (property tax, insurance, PMI, HOA) are not included; this models principal and interest only. Not modeled: prepayment penalties, servicer fees for third-party biweekly programs, rate changes on an adjustable loan, or recasting.
  • This is an estimate for educational purposes only, not financial advice. Confirm your loan's terms and whether your servicer accepts extra principal or biweekly payments without a fee before relying on these numbers.

Key terms

Definitions for the terms this calculator uses, in our finance glossary .

How it works

This calculator starts from your standard monthly payment, the normal principal and interest for your loan balance, rate, and remaining term, using the standard amortization formula. It then simulates a faster schedule one payment at a time.

Each period it charges interest on the balance you still owe (the annual rate divided by 12 for a monthly schedule, or divided by 26 for a biweekly one), rounds that interest to the cent the way a lender does, and applies the rest of the payment to principal. The balance falls a little faster every period because the extra principal you add, or the extra payment a year that a biweekly schedule creates, removes interest from every month that follows. The loop runs until the balance reaches exactly zero.

Two schedules are compared. The faster one uses your extra payment or biweekly cadence; the baseline is the standard monthly schedule with no extra. The interest saved and the time saved are the difference between them. With no extra and a monthly schedule, the two are identical, so the saving is zero.

A biweekly schedule means paying half the monthly amount every two weeks. That is 26 payments a year, which equals 13 full monthly payments instead of 12, so one extra monthly payment is made each year without you setting any money aside.

Worked example

Take a $300,000 balance at a 6% fixed rate with 30 years left. The standard monthly payment is $1,798.65, and paid on schedule the loan costs $347,515.44 in interest.

Now add $200 to every payment, for $1,998.65 a month:

  • The loan is paid off in 279 months instead of 360, which is 81 months, about 6.75 years, sooner.
  • Total interest falls to $256,341.57.
  • That saves $91,173.87 in interest for an extra $200 a month.

Switching instead to a biweekly schedule with no added principal pays half the payment, $899.33, every two weeks. The single extra payment a year clears the loan in about 294 months and saves $74,440.24 in interest. The earlier you start either approach, the more interest you erase, because interest is charged on the balance you still owe.

What is included (and what is not)

This models principal and interest only. Escrow items (property tax, insurance, PMI, HOA) are not part of the comparison. Not modeled: prepayment penalties, fees charged by third-party biweekly programs, rate changes on an adjustable loan, or recasting. All figures are nominal dollars and are not adjusted for inflation or taxes. Results are estimates for education, not advice; confirm your loan terms and whether your servicer accepts extra principal or biweekly payments without a fee.

Sources

Frequently asked questions

Do extra payments lower my monthly bill?
No, not on a standard mortgage. Extra principal shortens the term and cuts total interest, but the required monthly payment stays the same. The benefit shows up as fewer payments and less lifetime interest, not a smaller bill. Only a recast, where the lender re-amortizes after a lump sum, lowers the required payment.
Are biweekly payments really faster, or is it a gimmick?
They are faster, but the math is simple. Paying half your payment every two weeks means 26 half-payments a year, which equals 13 full monthly payments instead of 12. That one extra payment a year is the entire effect. You can get the same result for free by adding one-twelfth of your payment to each monthly payment yourself.
Why does paying extra early save more than paying extra later?
Because interest is charged on the balance you still owe. A dollar of extra principal applied early removes interest from every remaining month, so the same extra dollar saves more the earlier it is paid. That is why the saved interest grows faster than you might expect as the extra payment rises.
Should I watch out for biweekly payment program fees?
Yes. Some third-party services charge a setup or per-payment fee to do something you can usually do yourself for free. Before signing up, ask your servicer whether it accepts extra principal directly or offers a no-cost biweekly option. The Consumer Financial Protection Bureau notes you can often reach the same goal by making one extra monthly payment a year.

Related calculators

Learn how this works

New to this topic? Our companion guide explains it in plain language: Extra Mortgage Payments vs Biweekly: Which Pays Off Your Loan Faster?

Last reviewed June 2026.