How it works
How this tool works.
A little extra on every mortgage payment goes entirely to principal, and because interest compounds on the balance, shrinking that balance early pays off out of proportion to the amount. Even a modest monthly add-on can knock years off a loan and save a striking amount of interest over its life.
Enter the loan balance, rate, and years remaining, plus the extra you’d pay each month, and this calculator estimates the time and interest saved. It simulates the amortization schedule month by month for both plans and compares them — an illustration from your inputs, not a prediction or an offer.
Enter the current loan balance, interest rate, and years remaining; the tool computes the scheduled monthly principal & interest.
Add the extra principal you’d pay each month on top of that scheduled payment.
The calculator walks the amortization schedule for both the baseline payment and the payment-plus-extra, month by month, until each is paid off.
It reports the interest saved and the time saved — estimates from your inputs, assuming a fixed rate and that every extra dollar goes to principal.