Paying off a mortgage is a project measured in decades, which makes it easy to drift through on autopilot — same payment, same schedule, same distant end date. But borrowers who actively manage the payoff, rather than passively experiencing it, routinely finish years early and keep tens of thousands of dollars that would otherwise have gone to interest. The Paying Off Mortgage Calculator on this page builds your complete payoff plan. Enter your balance, rate, years remaining, and a potential extra monthly payment, and it returns your required payment, both payoff dates, months saved, interest under each scenario, and even the return ratio — how many dollars of interest each extra dollar saves you.