Mortgage Payoff Calculator

About this calculator

This calculator works out how many months remain on a loan by solving the standard amortization formula for time: n = −ln(1 − i·P/M) / ln(1 + i), where P is the current balance, i is the monthly interest rate, and M is the fixed monthly payment. Because interest is charged on the outstanding balance each period, the same payment amount pays off a loan faster once the balance is smaller — which is why extra principal payments shrink the payoff time by more than their dollar amount might suggest.

Homeowners deciding whether to make extra payments, borrowers comparing refinance offers with different rates and terms, and financial planners projecting when a mortgage will be paid off all use this calculation. It's the same math lenders use internally to build amortization schedules, just solved for payoff time instead of monthly payment.