Mortgage Payoff & Extra Payment Calculator

Enter your current balance, note rate, and remaining term, then add a recurring extra payment, a one-time lump sum, or both, to see the new payoff date and interest saved side by side with your original schedule.

Before you enter numbers

Use the remaining principal, note rate, and remaining term from your latest mortgage statement, not the original loan amount. A lender’s official payoff quote may differ slightly because it can include per-diem interest through a specific date and permitted fees.

Formula

i = annual rate ÷ 12; interest = opening balance × i; ending balance = opening balance − (payment − interest) − extra principal

Worked example

A $240,000 balance at 5.5% with 25 years remaining, adding $200 extra to principal every month, reaches zero balance measurably earlier than the standard schedule and cuts total lifetime interest — while keeping the original required payment unchanged if you ever need to pause the extra amount.

Recast vs. refinance vs. just paying extra

Extra payments keep your rate and term unchanged while shortening the loan. Recasting re-amortizes your remaining balance over the same remaining term after a lump sum, lowering the required payment without a new loan. Refinancing replaces the loan entirely and can lower the rate, but resets closing costs. Pick the one that matches whether you want a lower required payment, a shorter payoff, or a better rate.

Before you commit to a plan

Confirm two things with your servicer first: that extra payments are applied to principal (not held toward next month’s payment), and that your loan carries no prepayment penalty. Most current conventional loans have neither restriction, but older, portfolio, or non-QM loans sometimes do.

Limits and privacy

This tool provides a general educational estimate, not individualized financial, tax, or legal advice, and it does not compare mortgage prepayment against investing — any investment return used elsewhere would be an assumption, not a guarantee.

The calculation runs in your browser. Do not put loan numbers, account numbers, or other identifying information into a shareable link.

Related guide

Read Extra Mortgage Payments: What They Actually Save You for how amortization front-loads interest, the difference between recasting and refinancing, and why the “biweekly payment” trick is really just one extra payment a year.

Frequently asked questions

Does an extra payment always reduce principal?

Not automatically on every servicer — confirm the payment is marked “principal only” rather than applied toward a future due date.

Is a payoff quote the same as my online balance?

Not always; a payoff quote can include interest through a specific date and permitted fees.

Should I reduce my payment or shorten my term?

This calculator models keeping the scheduled payment and shortening the term. Ask your servicer about recasting if you’d rather lower the required payment instead.

Can I add an annual bonus as a lump sum?

Yes — enter it as a one-time principal payment in the month you expect to apply it.

Does this compare investing instead of paying down the mortgage?

No — it reports loan interest and time saved only.

Sources

• Consumer Financial Protection Bureau — “What is a payoff amount, and is it the same as my current balance?”, reviewed 2026-07-31