Loan payoff calculator

How it works

The calculator runs a month-by-month amortization simulation twice — once at your normal payment and once with the extra amount added — each month charging interest on the remaining balance at the monthly rate (annual rate divided by 12), applying whatever's left of the payment to principal, and stopping either when the balance hits zero or after 1200 months (100 years), which it treats as "never pays off."

FAQ

Why does it say the loan will never pay off?

That means your monthly payment is less than or equal to that month's interest charge, so the amount going to principal comes out zero or negative — the balance would grow forever rather than shrink, which the simulator catches and reports as unpayable rather than looping indefinitely.

Does the extra payment always go entirely to principal?

Yes, as modeled here — the simulation assumes 100% of any extra amount reduces principal with no added fees, which matches how most (but not all) lenders apply extra payments; check your loan's terms, since some require you to specify "apply to principal" or charge a prepayment penalty.