Mortgage extra payment calculator

See what an extra payment does to your payoff date and total interest. Everything runs in your browser.

Loan amount ($)

Interest rate (% per year)

Term (years)

Extra payment each month ($)

One-time extra payment ($)

Paid in month number

Standard amortization: the payment is fixed, interest accrues monthly on the remaining balance, extras go straight to principal. For education and planning only, not financial advice.

Want the full schedule, a refinance break-even comparison, and a biweekly view? See the Mortgage and Loan Payoff Calculator.