Finance
Mortgage Extra Payment Payoff Calculator
Estimate how a recurring extra mortgage payment changes payoff time and interest cost. The calculator uses new payoff months = iterative balance reduction using payment + extra principal. It returns more than one result so you can check the main answer against a useful secondary measure. A shorter term is meaningful only if the extra payment is affordable and the lender applies it to principal. This is an amortization scenario, not a lender statement; verify prepayment privileges and penalties.
Educational scenario only. Confirm rates, fees, taxes, contract terms, and eligibility with the relevant institution or adviser.
Calculate and compare
Use the number box for precision or the slider for fast scenario testing.
Scenario results
Projected payoff time
17 years 4 months
Assumes the same payment and rate throughout.
Months versus schedule
68
Positive means an earlier payoff.
Projected interest
$167,559.63
Interest from today through modeled payoff.
How the calculation works
Use consistent units and retain full precision until the final display step.
Worked example
Reproduce the displayed scenario, then change one assumption at a time.
Assumptions behind the result
- • Inputs use the units shown beside each control.
- • The displayed formula is applied without hidden market or demographic data.
- • Rounding occurs only for display; calculations keep full numeric precision.
- • A shorter term is meaningful only if the extra payment is affordable and the lender applies it to principal.
- • This is an amortization scenario, not a lender statement; verify prepayment privileges and penalties.
Mistakes that change the answer
- • Mixing percentages with decimals or mixing incompatible units.
- • Relying on a rounded intermediate value instead of the full result.
- • Changing several assumptions at once instead of testing current balance separately.