Extra Payment Mortgage Calculator
See exactly how much faster you’ll be debt-free — and how much interest you’ll save — by adding a little extra to each payment. Enter your loan, then try different extra amounts.
Why extra payments are so powerful
On a fixed-rate mortgage, your scheduled payment is split between interest (charged on the remaining balance) and principal. Early on, most of it is interest. An extra payment goes 100% to principal — so it not only shrinks the balance, it erases all the future interest that balance would have generated. That compounding is why a modest extra amount can remove years from a 30-year loan.
Use the “Extra monthly payment” field above and watch three things change instantly: your payoff time, your total interest, and the “loan balance over time” chart, which now drops to zero noticeably sooner. The amortization schedule below shows the new month-by-month path, and you can download it as CSV.
How to use the savings
Compare scenarios: try $50, $100 and $250 extra per month and note the payoff date and total interest for each. Pick the largest amount you can comfortably sustain — consistency matters more than size, because the earlier each dollar lands, the more interest it kills.
Frequently asked questions
How much does paying extra actually save?
It depends on your rate and how early you start, but on a typical 30-year loan even $100–$200 extra per month commonly cuts several years and tens of thousands in interest. Enter your numbers above for the exact figure.
Monthly extra vs one lump sum — which is better?
Both work. Monthly is easier to budget and saves interest every month; a lump sum makes a big one-time dent. Earlier is always better because interest accrues on the remaining balance.
Do extra payments lower my required payment?
No — they shorten the term, not the monthly amount. You finish sooner and pay less interest, but the scheduled payment stays the same unless you recast or refinance.
BriskToolbox provides estimates for general information only and is not financial advice. Check that your lender applies extra payments to principal and charges no prepayment penalty.