How loan payoff calculator works
Enter your loan principal, annual interest rate, and either the loan term in years or your scheduled monthly payment. The calculator derives the standard amortization schedule — the months and total interest it takes to pay the loan off with the scheduled payment alone.
Add an extra monthly payment on top of the scheduled payment. The calculator runs the schedule again with that extra amount applied to principal each month and reports the new payoff time and total interest.
The difference between the two schedules is your savings: months (and years) shaved off the loan and the interest you no longer pay. Extra payments go to principal, so the loan ends sooner and every skipped month also skips its interest.