Extra Mortgage Payment Calculator
Every extra dollar paid toward your mortgage principal reduces future interest and shortens your payoff timeline. Even $100/month extra can save tens of thousands over the life of a loan — this calculator shows exactly how much.
Enter your remaining balance, rate, term, and extra monthly payment to see total interest saved, years cut off, and a year-by-year balance comparison.
| Year | Balance (Standard) | Balance (With Extra) | Interest Saved to Date |
|---|
How Extra Mortgage Payments Work
When you pay more than your required monthly mortgage payment, the excess reduces your principal balance directly — as long as your lender applies it correctly. A lower principal means less interest charges every month going forward, which creates a compounding acceleration effect. Each extra dollar paid today eliminates multiple future dollars of interest because that principal would have kept accruing interest for years.
On a $400,000 mortgage at 7%, your first monthly payment is approximately $2,661. About $2,333 goes to interest and only $328 reduces principal. Adding $200/month roughly triples the principal reduction in year one — and that accelerated paydown compounds forward, shrinking the total interest snowball.
When Extra Payments Have the Biggest Impact
Early in the mortgage, extra payments are most powerful because you have more remaining principal — each extra payment eliminates a larger slice of the remaining interest stream. The same $200 extra paid in year 2 saves more total interest than $200 extra paid in year 20. This is why refinancing to a shorter term (15 years) and making extra payments from the start maximizes total savings — but it also means the savings from extra payments diminish over time, not increase.
| Extra Monthly Payment | Years Cut | Interest Saved | Return on Extra $ |
|---|---|---|---|
| $100/mo | 3.1 yrs | $41,200 | 3.3× extra paid |
| $200/mo | 5.8 yrs | $73,600 | 2.9× extra paid |
| $500/mo | 11.2 yrs | $128,400 | 2.1× extra paid |
| $1,000/mo | 16.4 yrs | $172,100 | 1.5× extra paid |
Ensure Your Extra Payment Reduces Principal
When making extra payments, always verify your lender applies the excess to principal, not the next month's payment. Most servicers allow you to designate extra payments as principal-only — either online, by phone, or by writing "principal only" on the check. If the extra payment is applied to next month instead, it saves no interest. Check your next statement to confirm the principal balance dropped by the extra amount.
Extra Payment vs. Investing: The Rate Decision
Paying extra on your mortgage is a guaranteed return equal to your mortgage rate — if your rate is 7%, every extra dollar saves exactly 7% in interest. Compare that to investing: S&P 500 averages ~10% annually over long periods but with significant year-to-year variance. Many financial advisors use 6%–7% as the crossover rate: above it, extra mortgage payments are competitive with investing; below it, investing typically wins. At today's rates (6.5%–7.5%), the choice is genuinely close and often comes down to personal preference for debt freedom vs. investment growth.
For a full guide on strategies to pay off your mortgage early — including biweekly payments, lump-sum windfalls, and refinancing to a shorter term — see our guide on when to refinance your mortgage. To see your full amortization schedule with extra payments, use the Amortization Schedule Calculator.
Frequently Asked Questions
How much does $200 extra per month save on a mortgage?
On a $380,000 balance at 7% with 28 years remaining, $200 extra per month saves approximately $73,600 in total interest and cuts about 5.8 years off the payoff timeline. The exact figure varies by balance, rate, and remaining term — use this calculator with your specific numbers for a precise answer.
Should I pay extra on my mortgage or invest?
Compare your mortgage rate to expected investment returns. Extra mortgage payments earn a guaranteed return equal to your mortgage rate (e.g., 7%). Stock market investments historically return ~10% but with significant volatility. Most advisors suggest extra payments are competitive above 6%–7% mortgage rates. Always max the 401k employer match before doing either — it's an instant 50%–100% return that beats both.
Do extra mortgage payments reduce the monthly payment or the term?
Extra payments reduce the term (number of payments remaining) and total interest paid — they do NOT automatically reduce your required monthly payment, which stays fixed. With a standard amortizing mortgage, making extra payments builds equity faster and shortens the payoff date, but your required payment each month stays the same unless you formally recast the mortgage.
How do I make sure extra payments go to principal?
Contact your mortgage servicer to confirm how to designate principal-only payments. Online portals typically have a "principal payment" option. On paper checks, write "principal only" in the memo. Always check your next statement to confirm the principal balance dropped by the extra amount — if it didn't, the payment was misapplied and needs to be corrected.
Is there a prepayment penalty for extra mortgage payments?
Most US mortgages originated after 2014 (qualified mortgages) have no prepayment penalty. Some older loans, jumbo loans, and non-QM loans may still include penalties, typically 2%–3% of the prepaid amount and often only applicable to large lump-sum payments. Check your original mortgage note or call your servicer to confirm before making a large extra payment.
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