How does an extra mortgage payment affect payoff time?
An extra payment can reduce a modeled payoff time when it is applied to principal. The CFPB explains that each mortgage payment includes principal and interest: principal reduces the amount owed, while interest is the borrowing cost. In a typical fixed-rate loan, the scheduled principal-and-interest payment stays level while the share going to interest declines as the balance falls. A lower balance then produces less interest in later modeled months.
This calculator compares two simplified schedules. First, it estimates the regular payment needed to amortize the remaining balance over the remaining term. Then it calculates that schedule month by month. In the second schedule, it adds the extra amount to principal after the regular payment. If that combined payment would exceed the payoff amount, the final payment is reduced to the exact modeled amount due.
For an illustration, enter a remaining balance of $300,000, a 6.5% annual rate, a 30-year remaining term, and $200 extra per month. These are example inputs, not a current mortgage offer or a forecast. Your result depends on your actual principal balance, interest rate, payment history, and servicer practices.
What payment should I enter as extra?
Enter only the additional amount you intend to send each month. The calculator adds this to the amortizing principal-and-interest payment it derives from your remaining balance, rate, and term. It does not accept or model escrow for property taxes, homeowners insurance, mortgage insurance, association charges, or other amounts that may be included in the total payment sent to a mortgage company.
The CFPB says borrowers may be allowed to make extra principal payments and recommends checking that extra amounts are applied to principal. Payment instructions and account terms matter. Review your mortgage statement or contact your servicer to confirm how to designate extra principal, whether there are fees or restrictions, and what happens if you pay more than the scheduled amount.
Why can this differ from a lender payoff quote?
This is a month-by-month estimate using a constant monthly rate. A lender's payoff amount is different from the balance shown on a statement: it can include interest through a specified payoff date and unpaid fees, and may reflect contract-specific requirements. This calculator does not compute a payoff quote or determine whether an early-payment charge applies. Ask the servicer for an official amount and check your note and disclosures.
The model also leaves out exact calendar dates, daily interest, payment delays, rate changes, recasts, skipped payments, and changes to the payment amount. It rounds the term to whole months and assumes the extra amount is paid every month and applied immediately to principal. Actual loan servicing and the loan documents control.
Primary sources checked 2026-11-03: CFPB, How does paying down a mortgage work?; CFPB, Your mortgage servicer must comply with federal rules; and CFPB, What is a payoff amount?
This tool is for education and arithmetic only. It is not financial, mortgage, tax, or legal advice.
Frequently asked questions
Does the calculator include taxes and insurance?
No. It models principal and interest only. Property taxes, homeowners insurance, mortgage insurance, escrow, and association fees are outside the calculation.
Will my servicer automatically apply extra money to principal?
Do not assume so. Check your servicer's payment instructions and verify how it applies an amount above the scheduled payment.
Does this calculate my official payoff quote?
No. A payoff amount can include interest through a particular date and other amounts owed. Request an official payoff statement from your servicer.
Does the estimate account for a prepayment penalty?
No. Review your loan documents and ask your servicer about any penalty, fee, or restriction that may apply to your loan.