Mortgage Payoff Calculator
Adjust the inputs below. Results update as you type.
How it works
Every extra dollar applied to principal reduces the balance on which future interest is calculated. Example: on a $300,000 30-year mortgage at 7%, paying $200/month extra saves over $90,000 in interest and pays off 7 years early. Round up to the nearest $100 for a simple strategy. Confirm your lender applies extra payments to principal immediately.
Input guidance
- Start from your current principal balance, not the original loan amount.
- Enter the rate and remaining term that match your statement.
- Model extra principal as a sustainable monthly amount you can keep paying.
The formula
Adding an extra amount X to each payment applies the surplus directly to principal. The payoff time shrinks because interest is recalculated on a faster-falling balance each month.
Worked example
On a $250,000, 30-year loan at 6%, adding $200/month pays it off about 6 years early and saves roughly $73,000 in interest.
More examples to test
- $280,000 balance at 6.5% with 24 years left + $200 extra/month: estimate interest saved and new payoff date.
- Apply a one-time $5,000 principal payment and compare timeline impact.
How to interpret results
Extra principal saves the most when applied early. Confirm your servicer applies extras to principal immediately.
When this can be inaccurate
ARM resets, escrow changes, and prepayment rules can differ from a fixed remaining-term model.
Change history
- July 2026: Published with extra-principal application and opportunity-cost caveats.
Site-wide corrections also appear on the corrections log.
Frequently asked questions
How does paying extra shorten the loan?+
Every extra dollar reduces principal immediately, so less interest accrues next month and the balance reaches zero sooner.
Is a lump sum or monthly extra better?+
Both help; earlier money helps more. A lump sum early in the loan removes the most future interest, but consistent monthly extras are easier to budget.
Should I check for prepayment penalties?+
Yes. Most modern US mortgages have none, but confirm with your lender before committing to an aggressive payoff plan.
Is paying off early always optimal?+
Not always. Compare the guaranteed interest savings with expected after-tax returns elsewhere and your liquidity needs.
Will my lender automatically apply extra payments to principal?+
Usually if labeled correctly, but confirm. Misapplied extras can sit in suspense or prepay future interest instead.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.