How does an extra mortgage payment reduce interest?

In this estimate, the extra amount reduces the modeled balance when it is applied. A lower balance generally means less interest is calculated in later periods, assuming the rate and payment rules remain unchanged.

How much time can an extra $100 per month save?

In the example above, adding $100 to the $1,896.20 monthly payment on a $300,000 balance at 6.50% reduces the modeled term from 360 scheduled payments to 312 months, a difference of 48 months. Interest falls from $382,636.74 to $321,640.90, a saving of $60,995.84. Your result depends on your balance, rate, payment, and timing.

How does the biweekly option work?

It models 26 payments per year, each one-half of the monthly-equivalent payment you enter. This equals 13 monthly-equivalent payments per year. Actual lender schedules and interest posting may differ.

Does the calculator show my official payoff amount?

No. It estimates the remaining payment schedule and interest from the inputs you provide. Contact your servicer for a date-specific payoff quote, which may include accrued interest and other charges.

Does the calculator include taxes, insurance, or escrow?

No. Enter the principal-and-interest portion of your payment. The estimate does not calculate property taxes, insurance, escrow, HOA charges, fees, or other housing costs.

Does it model mortgage recasting?

No. The lump-sum option adds the amount to the first modeled payment; it does not recalculate future scheduled payments. Ask your servicer about recasting eligibility and terms.

What does a lump-sum payment save?

On the same $300,000 balance at 6.50% with a $1,896.20 payment, a $10,000 lump sum applied at the start cuts the modeled term to 327 months and interest to $329,034.11, a saving of $53,602.63 across 34 fewer scheduled payments. A $25,000 lump sum cuts it to 286 months and $266,101.89, a saving of $116,534.85 across 75 fewer payments. The model applies the lump sum to the first payment, so a payment made later in the term would save less.

Is biweekly better than adding $100 a month?

Usually, because it moves more money. On the $300,000 example, biweekly payments of $948.10 clear the balance in 626 payments, which is 289 months, with $293,290.47 of modeled interest. Adding $100 a month clears it in 312 months with $321,640.90 of interest. The biweekly route is 23 months and $28,350.43 cheaper, because 26 half-payments a year equal 13 full payments, one extra payment of $1,896.20 annually, against $1,200 from the monthly increase. Confirm with your servicer that partial payments are applied immediately rather than held until a full payment accrues.

Will paying off early trigger a prepayment penalty?

Sometimes, so check the note before making a large extra payment. The CFPB's guidance on prepayment explains that many loans can be repaid early without a penalty while some carry one, usually limited to the first few years. A penalty changes the arithmetic that makes extra payments worthwhile, and this calculator has no field for it. If one applies, add its amount to the cost side and recompute the break-even: on the $300,000 example a $10,000 lump sum saves $53,602.63 of interest over the term, so a penalty well below that still leaves the move worthwhile, while a penalty on a small extra payment can wipe out years of saving.

Mortgage Payoff Calculator: Extra Payment Savings

Mortgage payoff timing depends on the remaining principal, payment schedule, and extra principal applied. This calculator compares a monthly or biweekly schedule and can model recurring, annual, or first-payment lump-sum extras. It uses your entered annual rate and P&I payment; the estimate is not a servicer's payoff quote.

The result is an estimate, not a lender payoff quote or a change to your mortgage contract. It assumes the payment amounts you enter are applied as modeled; your servicer's interest method, payment timing, fees, and handling of extra funds may produce different results.

How to Use the Mortgage Payoff Calculator

Current balance: The remaining mortgage principal, not the original loan amount or a payoff quote that includes accrued interest and fees.
Interest rate: The annual rate used for this estimate. The model holds it constant throughout the schedule.
Payment: Enter the principal-and-interest portion of your regular payment. Do not include property taxes, homeowners insurance, escrow, or HOA dues.
Payment schedule: Choose monthly or biweekly. In biweekly mode, enter your usual monthly-equivalent payment; the model uses half that amount every two weeks.
Extra payments: Add an amount with each modeled payment, an annual extra, a lump sum with the first modeled payment, or combine these options. The estimate assumes extras reduce the balance as scheduled.

How the estimate works

Monthly schedule baseline

For a monthly schedule, the calculator divides the annual rate by 12, calculates interest on the remaining balance for each modeled month, and applies the scheduled payment and any extras. The remaining balance falls faster when more is paid toward it, which can reduce interest in later periods. The calculation rounds money to cents and adjusts the final payment to clear the modeled balance.

How the biweekly 13th payment is modeled

Biweekly mode models 26 payments per year, each equal to half of the monthly-equivalent payment. That totals 13 monthly-equivalent payments per year. It converts the monthly rate to an equivalent biweekly period rate; it does not calculate actual daily interest or reproduce a particular lender's posting calendar. A recurring extra amount is also split in half for each biweekly payment. The annual extra is applied after each 12 monthly or 26 biweekly payment periods, and the one-time lump sum is included with the first modeled payment.

The estimated payoff date is based on the current date and the modeled payment count; it is not calculated from your next contractual due date. Biweekly terms are converted to an approximate month count for display.

Example payoff scenarios

Seven modeled plans at a glance

These illustrative calculations use a $300,000 current balance, a 6.50% annual rate, and a $1,896.20 monthly principal-and-interest payment. The fixed figures demonstrate the model; your result will depend on your inputs.

Modeled plan	Payment assumption	Payoff period	Time difference	Modeled interest	Interest difference
Monthly baseline	$1,896.20 / month	360 payments plus a $4.74 final payment in month 361	n/a	$382,636.74	n/a
Biweekly schedule, compared with monthly baseline	$948.10 every 2 weeks	626 periods (about 289 months)	71 months shorter	$293,290.47	$89,346.27 lower
$100 extra monthly	$1,996.20 / month	312 months (26 years)	48 months shorter	$321,640.90	$60,995.84 lower
$200 extra monthly	$2,096.20 / month	277 months (23 years, 1 month)	83 months shorter	$279,186.52	$103,450.22 lower
$350 extra monthly	$2,246.20 / month	238 months (19 years, 10 months)	123 months shorter	$234,452.37	$148,184.37 lower
$2,400 annual extra	$1,896.20 / month, plus $2,400 annually	279 months (23 years, 3 months)	82 months shorter	$283,639.74	$98,997.00 lower
$5,000 first-payment lump sum + $200 monthly extra	$2,096.20 / month	267 months (22 years, 3 months)	94 months shorter	$262,612.41	$120,024.33 lower

Which schedule the comparison rows assume

The biweekly row compares two separate schedules: the monthly baseline and a biweekly plan using half the same monthly-equivalent payment every two weeks. In the calculator, the baseline and extra-payment scenario use the schedule you select, so a biweekly run without extras is not itself a comparison against monthly payments.

A second balance, to show the scale changes

Smaller balances respond differently because the same extra dollar is a larger share of the payment. On a $150,000 balance at 4.50% with its contractual $760.03 payment, the baseline clears in 360 months with $123,609.26 of interest. Adding $100 a month clears it in 284 months (23 years, 8 months) with $93,891.34 of interest � 76 months earlier and $29,717.92 saved. The extra $100 saved less money in dollars here than in the $300,000 example, but a larger share of the loan's total interest, because the payment was already closer to the interest due each month.

Pay off the mortgage or invest the extra?

Every extra dollar sent to this schedule earns a guaranteed, pre-tax return equal to the loan's rate: in the $100-extra row above, each payment avoids interest that would otherwise accrue at 6.50%, and the guaranteed side of the comparison is the $60,995.84 of modeled interest the plan never charges. Investing the same dollar elsewhere has to beat that rate after tax and risk to come out ahead, and no market return is guaranteed. The calculator does not model investment returns or make the choice for you; it prices the guaranteed side so you can compare it against whatever alternative you are considering � this is a decision to make with your own full picture, not an instruction.

Before acting on an estimate

Check your mortgage documents or ask your servicer how additional funds are applied and whether your loan has any restrictions, fees, or prepayment terms. The calculator cannot determine those terms, guarantee that an extra amount will be credited to principal, or produce an official payoff amount. A lender payoff quote may include accrued interest, fees, and a date-specific amount that this estimate does not calculate.

Paying down a mortgage also changes how much cash remains available for other needs. Consider your full budget, emergency savings, other debt, taxes, and financial priorities before choosing a payment plan; this calculator does not compare those trade-offs or provide personalized financial advice.

To calculate baseline monthly payments, explore our Mortgage Calculator, examine full month-by-month equity crossover tables with our Amortization Calculator, or track general installment payoff milestones with our Loan Payoff Calculator.

The result is a payment-by-payment schedule rather than a chart, with the balance, interest, and principal visible month by month down to zero. The repayment formula underneath is the standard amortization walk at the rate you enter. To compare a reset of rate and term on the same house instead of paying it down early, use the Mortgage Refinance Calculator.

Provenance: every dollar figure in this article was computed by replicating the calculator's whole-cent balance walk (apps/tools/mortgage-payoff-calculator/logic.php) from the stated inputs, and verified in October 2026.

Last verified: October 2026. Results are computed from the inputs entered and do not reflect live bureau data, creditor balances, or a payoff quote.

Mortgage Payoff Calculator