Mortgage Payoff Calculator
Enter what you still owe and an extra monthly amount — the payoff date and interest savings update as you type.
How this calculator works
First we compute the regular monthly payment that would retire your balance over the remaining term — the standard amortization formula. Then we run the loan month by month twice: once with that payment alone, once with your extra amount added, sending every extra dollar straight to principal. Because interest each month is charged on the remaining balance, a smaller balance snowballs: each extra payment shrinks every future interest charge, which is why modest amounts save surprising sums.
Worked example
Owe $250,000 at 6.5% with 25 years left: the required payment is about $1,688.02 per month. Add $200 extra each month and the loan is gone in 19 years 6 months instead of 25 — you finish 5 years 6 months sooner. Lifetime interest falls from roughly $256,405 to about $191,477, an interest saving of about $64,928. Set the extra to $0 and both savings drop to zero; set it very high and the payoff collapses to a handful of months — the tool handles both extremes.
Frequently asked questions
Is paying extra on the mortgage better than investing the money?
It depends on the numbers and on you. Paying extra earns a guaranteed, tax-free return equal to your mortgage rate; investing may return more over long periods but is not guaranteed. Many people split the difference or prioritize the higher rate. This calculator shows one side of that comparison — the interest you'd save — so you can weigh it against realistic investment expectations. It is not personalized financial advice.
Do I need to tell my lender the extra money goes to principal?
Yes — this matters. Some servicers apply unlabeled extra funds to next month's payment or hold them in escrow, which saves you nothing. Mark the extra amount as a principal-only payment (most online portals have a field for it) and check your next statement to confirm the balance dropped by the extra amount.
How does the biweekly payment trick work?
Paying half your monthly payment every two weeks means 26 half-payments a year — the equivalent of 13 full monthly payments instead of 12. That one extra payment per year quietly accelerates payoff, similar to adding about 1/12 of your payment as a monthly extra. You can approximate it here by entering your monthly payment divided by 12 as the extra amount.
Can I be penalized for paying my mortgage off early?
Some loans carry prepayment penalties, usually only during the first few years and more commonly on non-conventional products. Most standard US mortgages written today have none, but the only way to know is your loan documents — look for a prepayment or early payoff clause, or ask your servicer for a payoff quote.