Mortgage Payoff Calculator

Enter your current balance, interest rate and remaining term, then add an extra monthly principal payment. The calculator amortizes the loan both ways to show your new payoff date, the months you save and how much interest you avoid.

Enter your loan details, then press Calculate payoff.

How extra payments help

A mortgage payment is split between interest (rate ÷ 12 on the current balance) and principal (the rest). Early on, most of it is interest. Any extra you pay goes straight to principal, which shrinks the balance that all future interest is charged on - so a small extra payment compounds into large savings.

monthly payment = P × r ÷ (1 − (1 + r)−n)

Here P is the balance, r is the monthly rate (APR ÷ 12) and n is the number of payments. The calculator works out your scheduled payment from your remaining term, then amortizes the loan month by month - once at the scheduled payment and once with your extra added - and compares them.

Worked example

A $280,000 balance at 6.5% with 28 years left, paying $200 extra a month:

Scheduled payment is about $1,800/month over 28 years.
Adding $200 sends $200 straight to principal every month.
Result: the loan clears years early and tens of thousands of dollars of interest never accrue - the tool shows the exact figures.

Where the savings come from

The earlier in the loan you add extra principal, the more interest you avoid, because that balance would otherwise have been charged interest for the longest time. Even one extra payment a year - paying biweekly, for example - can cut years off a 30-year loan. The calculator assumes a fixed rate and that extra payments are applied to principal; check that your lender does not charge prepayment penalties. Everything is computed in your browser.

Tip: see the full payment table with the amortization schedule calculator, or size a new loan with the mortgage calculator.

Frequently asked questions

Does an extra payment really save that much?

Yes. Extra money goes entirely to principal, reducing the balance every future interest charge is based on. Over a long loan the compounding effect can save tens of thousands of dollars.

Is it better to pay extra early or late?

Early. Principal paid in year one avoids interest for the entire remaining term, while the same dollar paid near the end avoids almost none. Earlier extra payments save the most.

What about prepayment penalties?

Most modern conforming mortgages have none, but some loans do. Check your note before committing to extra payments, since a penalty can offset part of the interest you save.

Are my figures uploaded?

No. The amortization runs entirely in your browser. Nothing you enter about your mortgage is sent to a server, logged or stored.

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Mustafa Bilgic · Editor, Calcool
Amortizes the loan month by month at a fixed rate, comparing the scheduled schedule with one that applies extra principal. Everything runs in your browser - nothing you enter is uploaded, logged or stored.

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