About the Extra Mortgage Payment Calculator
Every dollar you pay above your required mortgage payment goes straight to principal, shrinking the balance interest is charged on. Over time that compounds — modest extra payments can cut years off the loan and save tens of thousands in interest. This calculator simulates your payoff with the extra amount and shows the time and interest you'd save.
How it’s calculated
We build the normal amortization schedule, then run a second one that adds your extra monthly amount (and any one-time payment) to principal each month. The difference in payoff length and total interest between the two schedules is your savings.
Example calculation
On a $320,000 loan at 6.5% over 30 years, adding $200/month pays the loan off several years early and saves roughly $100,000 in interest over the life of the loan.
Frequently asked questions
Is it better to pay extra monthly or a lump sum?
Both help. A lump sum now removes interest on that amount for the whole remaining term, while steady monthly extras compound over time. Paying earlier saves more, so do whichever you can sustain.
Should I pay extra or invest instead?
Paying extra earns a guaranteed return equal to your mortgage rate. Investing may earn more but carries risk. If your rate is high or you value being debt-free, extra payments are compelling.
Do I need to tell my lender?
Usually you can add extra to a payment, but confirm it's applied to principal (not held or applied to future interest). Some lenders need a note or a separate principal-only payment.
This calculator provides estimates for educational purposes and should not be considered financial, tax, or legal advice. Your actual figures may vary with lender terms, fees, and market conditions.