Mortgage tools
Extra Mortgage Payment Calculator
Add an extra monthly amount, a one-time lump sum, or both—and see exactly how much interest you save and how many years come off your mortgage.
How to use this extra payment calculator
Enter your current loan amount, interest rate, and term. If you already have a mortgage, use your remaining balance, your note rate, and the years left on your original term so the month counting stays simple. Then add an extra monthly payment, a one-time payment, or both. For the one-time payment, choose the loan year and month in which you plan to send it—counting from your first payment.
The results compare two timelines side by side: paying only what is required, and paying with your extras. You will see both payoff dates, the total interest under each plan, the interest saved, and the time cut from the loan. The year-by-year table shows how the balance gap widens over time, and the full amortization schedule lists every month, including the extra principal in each payment. Results update instantly as you type—there is no submit button and no data leaves your browser.
This is an estimate only and not financial advice. Extra payments are assumed to be applied to principal in the month shown; check your servicer's rules for how extra amounts are posted.
Why extra principal works—and when to be careful
Early in a mortgage, most of each payment is interest. On a $350,000 loan at 6.5%, the first payment sends about $1,896 to interest and only about $316 to principal. Every extra dollar of principal removes a dollar that would have kept accruing interest for years, which is why extra payments made early are worth far more than the same dollars sent later. Our guide to extra mortgage payments works through the full example—including monthly extras, a lump sum, and biweekly payments—with a side-by-side comparison table.
Extra payments are not always the best use of cash. Build an emergency fund first, clear higher-interest debt, and capture any employer retirement match before accelerating a mortgage. Then confirm your servicer applies extra money to principal, not to next month's bill. For your full monthly housing payment including taxes, insurance, and PMI, use the mortgage PITI calculator.
Extra payment calculator FAQ
How do extra mortgage payments save interest?
Interest is charged on your remaining balance each month. An extra payment reduces that balance right away, so every later month accrues interest on less money. Your required payment stays the same, but more of it reaches principal and the loan ends sooner.
Is a lump sum or a monthly extra better?
A dollar sent earlier usually saves more than the same dollar sent later, because it stops accruing interest sooner. In practice, the best plan is the one you can sustain: many households combine a modest monthly extra with occasional lump sums from bonuses or tax refunds. Try both on this page and compare the interest saved.
Does this calculator include taxes, insurance, or PMI?
No. It models principal and interest only, because extra payments apply to the loan balance. Taxes and insurance do not change when you pay extra principal. Use the mortgage PITI calculator for a full monthly housing payment estimate.
Will my lender apply my extra money to principal?
Not always automatically. Some servicers apply extra funds to the next month's payment instead. Mark extra amounts "apply to principal" when you pay, use the principal-only payment option if your servicer offers one, and verify on your next statement that the balance dropped by the extra amount.
Should I always pay extra on my mortgage?
Not necessarily. An emergency fund, higher-interest debt, and an employer retirement match usually come first. Extra mortgage payments also make cash less liquid, because it sits in home equity. This calculator shows the savings side of the trade-off; the right choice depends on your full picture.
Are these numbers a lender quote?
No. This is an educational estimate only and not financial advice. It assumes a fixed rate, on-time payments, and extra amounts applied to principal in the month shown. Confirm details with your lender or servicer.