Mortgage Payoff Calculator
An extra payment on a mortgage is unlike almost any other use of money: it is applied entirely to the balance, and it cancels every future month of interest that balance would have charged. This shows what a given overpayment buys in years and in interest, and what the same money would have to earn elsewhere to beat it.
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Why an overpayment is worth more than it looks
A normal mortgage payment is split: part interest, part principal. An extra payment is not split at all. Every cent goes against the balance, and because interest is charged on the balance each month, that cent stops charging interest for every remaining month of the term. Early in a mortgage, when the balance is large and the term is long, a single extra payment can cancel two or three times its own value in future interest.
This is also why the effect shrinks as the mortgage matures. The same $250 a month applied in year twenty-five saves very little, because there is not much interest left to cancel.
The return is guaranteed, and it is your interest rate
Money paid against a 6.5 percent mortgage earns you 6.5 percent, risk-free and tax-free, because it is interest you would otherwise have paid. Nothing else available to an ordinary household is guaranteed at that level. That is the comparison to make: not whether the market might beat it, but whether you would accept a certain 6.5 percent over an uncertain 8.
Two things change the answer. If your mortgage interest is deductible, the effective rate is lower than the headline. And if you have an employer match on a retirement account, that match is an immediate 50 or 100 percent return, which beats any mortgage rate that has ever existed. Take the match first, always.
Do not overpay before the expensive debt is gone
A mortgage is almost certainly your cheapest borrowing. Credit cards at 22 percent and car loans at 9 make overpaying a 6.5 percent mortgage the wrong order of operations. Clear those first, keep an emergency fund intact, and only then start on the mortgage — because money paid into a house is extremely hard to get back out in a crisis, and a redraw facility is not the same as cash.
The biweekly trick, explained honestly
Paying half your mortgage every two weeks is often sold as a clever mechanism. It is not: 26 half-payments is thirteen monthly payments, so you are simply paying one extra month a year. You can get the identical result by dividing your payment by twelve and adding that to each month, without paying a service to arrange it. Both work well; only one of them is free.
Check for penalties and ask where the money goes
Some mortgages charge for early repayment, particularly in the first years, and some limit annual overpayments to a percentage of the balance. Where a penalty exists it can easily exceed the interest saved. Separately, when you send extra, tell the servicer to apply it to principal — left unmarked, many will simply hold it against next month, which achieves nothing at all.
Frequently asked questions
Is it worth paying extra on my mortgage?
It earns you a guaranteed return equal to your interest rate, which is hard to beat safely. Do it after clearing higher-rate debt, securing an employer retirement match and keeping an emergency fund.
How much difference does $100 a month make?
On a $285,000 balance at 6.5 percent with 27 years left, about three years off the term and $46,000 of interest. Raising it to $250 saves nearly seven years and $94,000 — more in total, but slightly less per dollar, because the earliest overpayments do the most work.
Does a biweekly payment plan work?
Yes, but only because it amounts to one extra monthly payment a year. You can do the same yourself for free by adding a twelfth of your payment each month.
Should I overpay or invest instead?
Overpaying is a certain return at your mortgage rate; investing is an uncertain, usually higher one. The honest comparison is certainty against expectation, and an employer match beats both.
Will extra payments lower my monthly payment?
Normally no — they shorten the term instead. Some lenders will recast the loan to lower the payment after a large lump sum, but you usually have to ask and pay a fee.