Extra Payment Payoff Calculator
Extra Payment Payoff Calculator: Enter your loan balance, rate, remaining term and a monthly extra payment to see how many months earlier you'd be debt-free and how much interest you'd save versus paying only the minimum.
Data as of 2026-06-14.
Estimates only — for general education, not financial advice. See our disclaimer.
The formula
Compare payoff time at the normal payment vs (normal payment + extra)
We amortize the balance twice: once at your regular monthly payment and once with your extra payment added. The difference in months and in total interest is your saving. Extra payments go straight to principal, so every dollar removes future interest on that dollar.
How it works
- Extra payments apply directly to principal, shrinking the balance interest is charged on.
- The earlier in the loan you add extra, the more interest you avoid — front-loaded savings.
- Even a small recurring extra (e.g. rounding up) can cut years off a 30-year mortgage.
- Confirm your lender applies extra to principal and check for any prepayment penalties.
Frequently asked questions
How much do extra payments save?
Because extra payments reduce principal directly, they remove all the future interest that principal would have generated. On a long mortgage, an extra $100–$300 a month can save tens of thousands in interest and cut years off the term — enter your numbers above to see your figure.
Is it better to make extra payments or invest?
It depends on your loan rate versus your expected after-tax investment return. Paying extra is a guaranteed return equal to your loan's rate; investing may earn more but carries risk. Many people split the difference.
Do extra payments lower my monthly payment?
No — on most loans the required monthly payment stays the same; you just pay the loan off sooner. Some lenders offer 'recasting' to lower the payment after a large principal payment.
When do extra payments help most?
Early in the loan, when the balance and the interest share of each payment are highest. The same extra dollar saves far more interest in year 1 than in year 25. This is an estimate, not financial advice.
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Last updated: 2026-06-14