Mortgage payoff calculator
Pay off your mortgage sooner. Add an extra monthly or one-time payment and see how many years it cuts off — and how much interest you save. No email, no lender.
Rate prefilled with today’s ~30-yr average (7.424%) from our live board — edit freely.
How extra payments pay off your mortgage sooner
Your scheduled payment is split each month between interest (charged on the balance) and principal. Any extra you add goes entirely to principal, permanently shrinking the balance that interest is charged on — for every remaining month. That compounding is why a small recurring extra, or a lump sum early on, can cut years off a 30-year loan and save a large slice of total interest. This calculator amortizes your loan twice — with and without the extra — and shows the difference.
Extra payments vs. investing
Paying down a mortgage is a guaranteed return equal to your interest rate. Investing may beat that over time but is not guaranteed. The right call depends on your rate, your after-tax expected returns, and how much you value being debt-free. Know your real rate first — see today’s board — then run both scenarios here.
A worked example
Take a $300,000 balance at 6.5% on a 30-year term — a payment near $1,896/month, with about $382,000 in interest over the full term if you never pay extra. Add just $200/month to principal and the loan pays off roughly 5 years early, saving on the order of $67,000 in interest. The reason is compounding in reverse: that first extra $200 stops accruing 6.5% interest for the entire remaining life of the loan, and every month’s extra does the same. A one-time lump sum early on works even harder, because it removes interest over the longest horizon.
What trips people up
- Assuming the servicer applies it right. Extra money can be parked toward your next payment instead of principal. Tell your servicer, in writing, to apply extra to principal.
- Overlooking higher-rate debt. If you carry credit-card or other debt above your mortgage rate, a dollar there usually beats a dollar on the mortgage. Clear the costlier debt first.
- Draining the emergency fund. Mortgage prepayment is illiquid — you can’t easily pull it back out. Keep reserves intact before accelerating the loan.
Common questions
How much do extra payments save?
Every extra dollar goes straight to principal, so it stops accruing interest for the whole remaining life of the loan. Even a small recurring extra payment can cut years off the term and save tens of thousands in interest — this calculator shows exactly how much for your loan.
Is it better to pay extra monthly or one lump sum?
Both help; the sooner the money hits principal the more it saves. A recurring monthly extra is usually easiest to sustain, while a one-time lump sum early in the loan has an outsized effect. You can enter both here and see the combined result.
Should I make extra payments or invest instead?
It depends on your mortgage rate versus expected after-tax investment returns, your risk tolerance, and the guaranteed nature of interest saved. Paying down a mortgage is a guaranteed return equal to your rate; investing may return more but is not guaranteed.
By L.W. Martin, Founder — 20 years in the mortgage business, including 15 running his own brokerage. About → · Updated September 2026.