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Mortgage Prepayment Calculator

Estimate how extra monthly mortgage payments may shorten payoff time and reduce interest.

Updated April 11, 2026
Free online tool
Planning and research use

Why this page exists

Extra mortgage payments can look small each month while still taking years off the loan. This calculator helps homeowners estimate how a steady extra payment may change the payoff timeline and total interest so it is easier to judge whether the extra cash flow is worth directing to the mortgage.

Interactive tool

Run the estimate

Enter your numbers and read the result first, then use the sections below to understand what affects the outcome.

Calculator

Mortgage prepayment calculator

Estimate how extra monthly mortgage payments could shorten payoff time and reduce interest.

Result

19 years 7 months

Estimated payoff timeline with the extra monthly payment applied on top of the regular mortgage payment.

New estimated payoff time19 years 7 months

Interest saved$76,370.30

Time reduced5 years 5 months

Regular monthly payment used$2,044.98

Adding $250.00 each month shortens payoff from about 25 years to about 19 years 7 months.
That change saves roughly $76,370.30 in interest under the same rate assumption.
This estimate assumes the extra amount goes to principal consistently each month and the mortgage terms do not change.

This is a planning estimate. Real mortgage servicing rules, prepayment timing, escrow changes, and lender fees can change the exact outcome.

Planning note

Last updated April 11, 2026. Use this tool to compare scenarios and plan ahead, then confirm important details with the lender, employer, insurer, contractor, or other qualified provider involved in the final decision.

How it works

What the calculator is doing

Enter the current loan balance, interest rate, and remaining loan term.

Use your regular monthly payment or leave it at 0 to estimate one from the balance, rate, and remaining term.

Add an extra monthly payment to compare the standard payoff path with a faster one.

Understanding your result

The real value here is the comparison. Seeing how many months disappear and how much interest falls can make an extra payment feel more concrete than a vague idea of paying the loan off faster someday.

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Examples

Ways people use this tool

Example scenarios help turn a quick estimate into a more useful comparison or planning step.

Test a small recurring prepayment

Even a modest extra monthly amount can show whether the payoff timeline moves enough to matter for your budget goals.

Compare no prepayment vs a larger prepayment

Run the calculator twice to see how much extra monthly cash flow changes the savings.

Use the estimated payment when you only know the balance

If the regular payment is not handy, the calculator can estimate one from the remaining balance, term, and rate.

FAQ

Common questions

Do I need to know my exact current payment?

No. You can enter it if you know it, but the calculator can also estimate a regular payment from the balance, rate, and remaining term.

Why do extra payments save so much interest?

Because sending extra money to principal earlier reduces the balance that future interest is charged on month after month.

Will my lender apply extra payments the same way?

Not always. This calculator assumes the extra amount is applied to principal consistently, so check your servicer rules for how prepayments are actually handled.

Related tools

Keep comparing

Use these related tools to compare nearby scenarios, check a second estimate, or keep narrowing down the right decision.

Home ToolsUpdated April 11, 2026