Mortgage Payoff Calculator
The extra-monthly path and the one-time path are calculated separately.
Published by the Mortgage Guide editorial team. Rate assumptions and content updated October 2026. This page is educational. It is not a loan offer, approval, or personalized financial advice.
How this calculator works
- The current path amortizes the balance at the rate and remaining term you enter.
- The extra-monthly path adds the same extra amount to every payment.
- The one-time path applies a single extra amount on the first payment.
- Interest saved is the current path's interest minus the alternative path's interest.
A lower payment and an earlier payoff are different goals
Sending extra principal does not change the required monthly payment unless the servicer recasts the loan. It reduces the balance, which can cut interest and move the payoff date earlier.
Use one comparison at a time. Adding both the extra monthly amount and the lump sum together would overstate the savings, so this page does not do that.
Sources
Common questions
Is there a prepayment penalty?
This calculator does not know your note. Some loans restrict prepayment. Check the note or ask the servicer before assuming extra principal is free to send.
Which path saves more?
It depends on the amounts you enter. The page shows interest saved and months saved for each path against the current schedule.
Related calculators
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Build a monthly or annual mortgage amortization schedule, with an optional extra payment and a CSV download.
- Biweekly Mortgage Payment Calculator
Compare a monthly mortgage with 26 half-payments a year, which equal 13 full monthly payments.
- Mortgage Refinance Calculator
Compare your current mortgage payment with a new rate and term. Break-even appears only when the new payment is lower.
Longer guides on these topics are linked from the guides library.