mortgage calculator

Mortgage Payoff Calculator

The Mortgage Payoff Calculator compares a current fixed-rate payoff path with an alternate payoff path. Known Remaining Term mode derives the current balance from the original loan amount, original term, remaining term, and entered rate. Statement Balance mode starts from the unpaid principal balance and current monthly payment shown by the user. The repayment option then models normal payments, extra monthly, yearly, or one-time payments, a biweekly-style shortcut, or payoff now.

Result

Result summary: Payoff in 17 years and 3 months, saving $122,306.20 in remaining interest.
Remaining balance: $372,217.43
Baseline monthly payment: $2,398.20
Payoff monthly payment: $2,898.20
Original payoff months: 300
Original payoff time: 25 years
Payoff months: 207
Payoff time: 17 years and 3 months
Time saved months: 93
Time saved: 7 years and 9 months
Original remaining interest: $347,243.20
Payoff remaining interest: $224,937.00
Interest saved: $122,306.20
Original remaining payments: $719,460.63
Payoff remaining payments: $597,154.42
What this means: Payoff estimate assumes fixed interest, no new borrowing, no escrow changes, and no prepayment penalty.

Scenario nameNotes

Save this result, then use saved scenarios to switch between assumptions.

How the Mortgage Payoff Calculator works

Use this calculator when you want to compare how extra principal assumptions may affect payoff time and remaining interest under this app's fixed-rate monthly model. Use Mortgage Payment for a new principal-and-interest payment estimate, Amortization for a schedule-style summary, Refinance when a new loan replaces the current one, and lender or servicer payoff statements or documents for an actual payoff amount, payment-allocation instruction, prepayment penalty, escrow change, legal disclosure, or product-specific rule.

The app converts originalLoanTermYears to originalTermMonths and combines remainingTermYears * 12 + remainingTermMonths. In Known Remaining Term mode, it solves the original fixed payment from originalLoanAmount, annualRate / 100 / 12, and originalTermMonths, then derives remainingBalance after originalTermMonths - remainingMonths elapsed payments. In Statement Balance mode, remainingBalance equals unpaidPrincipalBalance and baselineMonthlyPayment equals currentMonthlyPayment. The simulator accrues monthly interest as balance * annualRate / 100 / 12, applies the baseline payment plus selected extras, adds oneTimePayment in the first payoff month, adds extraYearlyPayment every 12th payoff month, models biweekly-style repayment as baselineMonthlyPayment / 12 extra each month, caps the final principal payment to the remaining balance, and stops at payoff or the 1200-month safety cap. Interest saved equals baseline remaining interest minus selected payoff remaining interest.

Mortgage Payoff Calculator formula

This formula page covers the app's Mortgage Payoff Calculator: a fixed-rate remaining-balance payoff simulation that compares the current payoff path with an alternate path using extra monthly, yearly, one-time, biweekly-style, or payoff-now assumptions. It estimates remaining balance, baseline payment, payoff payment, payoff months, remaining interest, payment totals, time saved, and interest saved. It is not a servicer payoff statement, lender quote, payment-allocation instruction, prepayment-penalty answer, escrow estimate, tax answer, legal disclosure, refinancing recommendation, or personalised borrowing advice.

r = annualRate / 100 / 12; N0 = originalLoanTermYears * 12; Nrem = remainingTermYears * 12 + remainingTermMonths; PMT0 = fixedPayment(originalLoanAmount, r, N0); B0 = knownTerm ? remainingBalance(originalLoanAmount, r, PMT0, max(0, N0 - Nrem)) : unpaidPrincipalBalance; I_m = B_(m-1) * r; Pay_m = PMT0 + extraMonthly + biweeklyExtra + yearlyExtra_m + oneTime_m; Principal_m = Pay_m - I_m; B_m = max(0, B_(m-1) - Principal_m); InterestSaved = baselineInterest - payoffInterest

Known Remaining Term mode derives the current balance from the original loan and elapsed months. Statement Balance mode starts from the entered unpaid principal balance and current payment. The payoff simulation then accrues monthly interest, applies payments first to interest, reduces principal, and compares the baseline schedule with the selected extra-payment path.

Symbol	Meaning	How this page uses it
r	Monthly rate	The entered annual rate divided by 100 and by 12.
N0	Original term months	Original loan term years multiplied by 12.
Nrem	Remaining term months	Remaining term years multiplied by 12, plus remaining term months.
Elapsed	Elapsed months	Known Remaining Term mode uses max(0, original term months minus remaining term months).
PMT0	Baseline monthly payment	Known Remaining Term mode solves a fixed payment from the original loan, rate, and original term; Statement Balance mode uses the entered current monthly payment.
B0	Starting payoff balance	Known Remaining Term mode derives the remaining balance after elapsed payments; Statement Balance mode uses unpaid principal balance.
I_m	Monthly interest	Starting balance for month m multiplied by the monthly rate.
Pay_m	Scheduled payment for month m	Baseline payment plus applicable extra monthly, one-time, yearly, or biweekly-style amounts.
Principal_m	Principal reduction	Scheduled payment minus monthly interest. If this is not positive, the app stops at the 1200-month safety cap.
B_m	Balance after month m	Prior balance minus principal reduction, floored at zero when the payoff completes.
InterestSaved	Interest saved	Baseline remaining interest minus payoff-path remaining interest, floored at zero.

Step by step

Read loan information mode, original loan amount, original term, remaining term, unpaid principal balance, current monthly payment, annual rate, repayment option, and extra-payment fields.
Convert the annual percentage rate to a decimal monthly rate by dividing by 100 and by 12.
Convert original term and remaining term to months.
In Known Remaining Term mode, solve the original fixed payment and derive the current remaining balance from original loan amount, rate, payment, and elapsed months.
In Statement Balance mode, use the entered unpaid principal balance as the starting balance and the entered current monthly payment as the baseline payment.
Run a baseline monthly simulation with no extra payments to estimate original payoff months, remaining interest, and remaining payments.
Run the selected payoff path: extra-payment mode applies monthly extras each month, one-time extra in month 1, and yearly extra every 12th month.
For biweekly-style mode, add one-twelfth of the baseline monthly payment each month, approximating 13 monthly payments per year rather than modeling actual biweekly servicer processing.
For payoff-now mode, set payoff months to 0, interest to 0, and payoff monthly payment to the starting balance.
Each simulated month accrues interest first, then applies the scheduled payment to interest before reducing principal.
If the scheduled payment does not cover monthly interest, return the 1200-month safety cap so the page does not imply the loan amortizes.
Calculate time saved as baseline months minus payoff months, and interest saved as baseline remaining interest minus payoff remaining interest.
Round displayed currency outputs after the monthly simulation.

Worked example

Default, statement-balance, biweekly-style, and payoff-now examples

These examples use the app's package fixtures and branches so the numbers match the production formula rather than a servicer payoff quote.

Default known-term fixture: $400,000 original loan, 30-year original term, 25 years remaining, 6 percent rate, and $500 extra per month.
Known Remaining Term mode derives a $372,217.43 remaining balance and a $2,398.20 baseline monthly payment.
Adding $500 per month raises the modeled payoff payment to $2,898.20, shortening payoff from 300 months to 207 months.
The default fixture reports 17 years and 3 months payoff time, 7 years and 9 months saved, $224,937.00 payoff remaining interest, and $122,306.20 interest saved.
Statement-balance fixture: $250,000 unpaid principal balance, $1,800 current payment, 5.75 percent rate, $250 monthly extra, $1,000 yearly extra, and $5,000 one-time extra.
That fixture reports payoff in 14 years, compared with 19 years and 2 months on the baseline path, and $50,115.04 interest saved.
Biweekly-style fixture: $300,000 unpaid balance, $2,100 current payment, and 6.25 percent rate. The app adds $175 per month, which is one-twelfth of the baseline payment.
That fixture reports $2,275.00 payoff monthly payment, 18 years and 8 months payoff time, and $42,471.01 interest saved.
Payoff-now mode is a separate branch: the app treats the starting balance as the payoff payment and reports 0 payoff months and 0 additional simulated interest.

The formula compares simplified fixed-rate scenarios. A real payoff amount can differ from a current balance because of accrued interest through a payoff date, fees, escrow, payment timing, payoff instructions, or a prepayment penalty.

Assumptions and what this calculator ignores

Geographic scope: works globally. The math is currency-agnostic, so enter amounts in your own currency; local taxes, fees, and product rules are not included.

The calculator models one fixed-rate monthly principal-and-interest payoff path. It does not model adjustable rates, daily accrual, escrow changes, taxes, homeowners insurance, mortgage insurance, HOA dues, late fees, skipped payments, recasts, refinancing costs, lender credits, new borrowing, negative amortization, payoff statement fees, lien-release fees, or product-specific contract terms.
Extra payments are modeled as principal additions inside this app's schedule: monthly extras every month, yearly extras on every 12th payoff month, one-time extras in the first payoff month, and biweekly-style repayment as one extra monthly payment spread across 12 months. Real servicers may apply payments first to fees, past-due amounts, current interest, escrow, future-payment credits, or other buckets before reducing principal.
Package fixtures cover known-term extra monthly, statement-balance mixed-extra, and biweekly-style payoff paths, and internal independent comparator checks may be used only as validation evidence. CFPB payoff amount materials are needed before explaining current balance versus payoff amount; CFPB mortgage amortization materials are needed before explaining principal and interest allocation; CFPB prepayment-penalty materials and lender or servicer documents are needed before making extra-payment application, early-payoff, principal-only, or penalty claims; and Regulation Z sections 1026.36(c)(3) and 1026.41 are needed before legal payoff-statement or periodic-statement claims. Results are educational estimates, not financial, tax, legal, lending, mortgage, consumer-rights, regulatory, or personalised advice.

What this formula does not include

The result is not a servicer payoff statement, payoff quote, lender disclosure, payment-allocation instruction, payoff-fee answer, prepayment-penalty answer, escrow analysis, tax answer, insurance estimate, legal conclusion, refinancing recommendation, or personalised borrowing advice.
The app models monthly fixed-rate interest. It does not model daily interest accrual, exact payoff dates, cut-off times, wire fees, recording fees, release fees, late fees, suspense accounts, unapplied funds, delinquency, bankruptcy, foreclosure, loss mitigation, adjustable rates, interest-only periods, balloon payments, recasts, or loan modifications.
Known Remaining Term mode derives a balance from original loan details and remaining term. If the real loan has had previous extra payments, missed payments, payment changes, fees, escrow changes, or servicing adjustments, the derived balance may not match the statement balance.
Statement Balance mode depends on the entered unpaid principal balance and current monthly payment. A current balance is not necessarily the amount required to fully pay off the mortgage.
Extra-payment mode assumes the extra amount reduces principal after monthly interest is covered. Real servicers can have payment instructions, partial-payment, suspense, fee, escrow, or principal-only rules that must be checked in servicer documents.
Biweekly-style mode is an approximation of one extra monthly payment per year. It does not model actual 26-payment processing, servicer batching, due dates, or third-party biweekly payment programs.
Payoff-now mode does not add accrued interest through a specified payoff date, unpaid fees, recording costs, release costs, escrow shortages, or penalties.
The 1200-month cap prevents infinite schedules when the modeled payment does not amortize the balance; it is not a lender hardship, modification, foreclosure, or affordability analysis.
Currency outputs are rounded for display after full-precision monthly simulation, so hand calculations that round each month can differ by a few cents.
Internal validation artifacts are not public source citations; these formula notes rely on app derivation, deterministic fixtures, and official source boundaries.
The result is educational only and does not constitute financial, tax, legal, lending, mortgage, consumer-rights, regulatory, housing, or personalised advice.

Common mistakes to avoid

Reading the result as a servicer payoff quote. A real payoff amount can differ from current balance because it may include interest through a specified date, unpaid fees, and any applicable payoff or prepayment terms.
Assuming every extra amount is applied immediately to principal. The app applies extras that way for modeling, but real allocation rules depend on the lender, servicer, account status, payment method, loan documents, and jurisdiction.
Treating biweekly-style as an exact calendar schedule. The app approximates it as one extra monthly payment per year spread across months; actual biweekly billing, payment dates, and servicer statements can work differently.

Key terms

Payoff amount: The amount needed to fully satisfy a mortgage as of a specified date. The calculator estimates payoff mechanics, but a real payoff amount comes from the lender or servicer and can include accrued interest, unpaid fees, and loan-specific terms.
Extra principal: Extra money the app models as reducing the mortgage balance faster. This can lower later interest in the simulation, but real servicer allocation rules need account documents.
Biweekly-style: The app's shortcut for approximating 13 monthly payments per year. It adds one-twelfth of the baseline monthly payment each month rather than modeling exact calendar payment dates.

Frequently asked questions

How do I calculate my mortgage payoff amount?

Give the calculator either your remaining term or your unpaid principal balance. In known-term mode it rebuilds your original payment from the original loan amount, rate, and term, then derives the remaining balance mathematically; in balance mode you enter the balance from your statement (the default example uses $250,000 at 6 percent). Note that a servicer's official payoff quote adds accrued interest through the payoff date and any fees, so it will differ from a statement balance.

When will my mortgage be paid off?

The calculator simulates your loan month by month at your fixed rate and current payment and reports the baseline payoff date, then shows the alternate path with any extra payments you add. With the defaults - $250,000 remaining at 6 percent with a $1,800 payment plus $500 extra per month - it reports both payoff timelines and the months of payments you avoid, so the answer is specific to your numbers rather than a rule of thumb.

How can I pay off my mortgage faster?

The calculator models the four common acceleration strategies: a fixed extra amount every month, an extra lump sum once a year, a single one-time payment, and a biweekly-style schedule that effectively makes one extra monthly payment per year. For each it reports the new payoff date, months saved, and interest saved against your baseline, so you can compare strategies with the same assumptions before committing money.

Why is my payoff amount higher than my current balance?

A statement balance is a snapshot after your last payment posted, while a real payoff amount adds interest that accrues daily until the payoff date, plus any payoff processing fees, recording fees, or escrow adjustments. This calculator models monthly interest on the remaining balance, which is close but not identical to servicer daily accrual - request an official payoff statement before wiring funds.

Do extra mortgage payments lower my monthly payment or shorten the term?

On a standard fixed-rate mortgage, extra principal shortens the term and cuts total interest, but the required monthly payment stays the same - that is exactly how this simulation models it. The scheduled payment keeps its size while more of each payment goes to principal. If you want a lower required payment instead, that is a recast or refinance conversation with your servicer, which this calculator does not model.

Methodology, sources, and disclaimer

This calculator is an original implementation based on the app's documented fixed-rate mortgage payoff simulation, remaining-balance derivation, extra-payment assumptions, deterministic fixtures, edge cases, rounding policy tests, and internal validation. It is not copied from a single source.

Outputs are checked with deterministic fixtures, edge cases, rounding policy tests, and internal validation artifacts. The result remains an educational estimate, not a servicer payoff statement, payoff quote, lender disclosure, payment-allocation instruction, prepayment-penalty answer, escrow analysis, tax answer, legal conclusion, refinancing recommendation, or personalised borrowing advice.

Formula version 2026.05.22-generic-mortgage-payoff. The version marks the calculation logic and validation fixture set used for this estimate.

CFPB payoff amount materials should be used when copy explains current balance versus payoff amount, accrued interest through a specified payoff date, unpaid fees, or servicer payoff quotes.
CFPB mortgage amortization and principal-and-interest materials should be used when copy explains how fixed-rate mortgage payments split between principal and interest over time.
CFPB prepayment-penalty materials and lender or servicer documents should be used before copy makes extra-payment application, principal-only payment, early-payoff, biweekly-processing, payoff-fee, or prepayment-penalty claims.
Regulation Z sections 1026.36(c)(3) and 1026.41 should be used before copy discusses legal payoff-statement timing, payoff-statement accuracy, periodic-statement requirements, or biweekly billing-cycle disclosure treatment.

Results are educational estimates, not advice. Read the full disclaimer.

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