🧮 Calculators · Updated October 8, 2026 · 7 min read

Extra Mortgage Payments: What You Save in Interest

Adding $200 a month to a $360,000 mortgage at 6.5% saves about $109,000 in interest and pays the loan off six years early. Extra mortgage payments work because every dollar goes straight to principal, and principal is what interest is charged on. The effect is largest early in the loan, when most of each payment is interest. Below are the real figures for common strategies, the fine print that decides whether your extra money is applied correctly, and the situations where paying ahead is not the smartest use of cash.

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Mortgage calculator for a $385,000 home with 10% down at 6.25% over 30 years, showing a $3,045 monthly payment, $346,500 loan, $320,346 total interest and Jul 2050 payoff — Your complete monthly payment, total interest and payoff date in one view.

💡 Why a small extra payment moves the payoff date so much

In month one of a 30-year, $360,000 loan at 6.5%, the required payment is $2,275.44, yet only $325 of it reduces the balance; the other $1,950 is interest. An extra $200 therefore raises that month's principal reduction by more than 60%. Each dollar you prepay also stops generating interest for every remaining month of the loan, so its benefit compounds quietly in your favor. That is why the savings are counted in tens of thousands of dollars rather than in the few thousand you might expect.

How much extra mortgage payments save: the numbers

All examples use a $360,000 balance, a 6.5% fixed rate and a 30-year term. With no extra money the borrower pays about $459,160 in interest over 360 payments.

$100 extra per month: interest falls to about $396,250, saving roughly $62,900, and the loan ends after 26 years 7 months
$200 extra per month: interest falls to about $350,240, saving roughly $108,900, with payoff in 23 years 11 months
$500 extra per month: interest falls to about $263,030, saving roughly $196,100, with payoff in 18 years 9 months
One extra full payment a year, spread as about $190 a month: saves roughly $104,700 and finishes in about 24 years 2 months
A single $10,000 lump sum in the first month: saves roughly $54,500 and trims about 2 years 4 months

Notice the timing effect in the last line. A one-time $10,000 early in the loan saves almost as much as $100 a month for decades, because it has the longest runway to stop interest from accruing.

Biweekly plans, lump sums and recasting

There are several ways to prepay, and they differ in flexibility more than in math.

Biweekly: paying half the monthly amount every two weeks produces 26 half payments, or 13 full payments a year; you get the same result by adding one twelfth of a payment each month
Third-party biweekly services sometimes charge setup or per-payment fees for something you can do yourself for free
Lump sums from a bonus or tax refund work best early; the same check in year 25 saves far less
A recast lets you pay a large lump sum and ask the lender to recalculate a lower required payment on the same term, usually for a fee of a few hundred dollars

Prepaying shortens the loan but does not lower the required payment. If you want a smaller monthly bill instead of an earlier payoff date, a recast is the tool to ask about.

Make sure the extra goes to principal

The savings above only happen if your servicer applies the money to principal immediately. Some servicers hold unlabeled extra money as a future payment or put it in suspense.

Choose the principal-only option in your servicer's online portal, or write principal only on the memo of a check
Check the next statement and confirm the principal balance dropped by the full extra amount
Most loans made since 2014 have no prepayment penalty, and where one exists it is limited to the first three years; still, read your note
On conventional loans, extra principal also gets you to 20% equity sooner, so you can request PMI removal earlier

When paying extra is not the best move

A guaranteed 6.5% return by avoiding interest is excellent, but it is not the only priority, and money sent to the lender is hard to get back.

Build an emergency fund of three to six months of expenses first, since home equity is not cash when you lose a job
Pay off credit cards and other debts charging more than your mortgage rate before prepaying the mortgage
Capture any employer retirement match, which is an instant return no mortgage prepayment can beat
On a loan below 4%, many people prefer high-yield savings or investments that can earn more than the loan costs

A balanced approach is common: meet those priorities, then direct a fixed extra amount to the mortgage automatically so it happens without monthly decisions.

Run your own loan through the Mortgage Calculator, and test the invest-instead option in the Compound Interest calculator.

Step-by-step

1Open the Mortgage Calculator and enter your home price, down payment, current rate and original loan term so the loan amount matches your statement.

Mortgage calculator loan fields filled in: $385,000 home price, 10% down payment, 6.25% interest rate and a 30-year term — Enter the home price, down payment, rate and term — the payment updates as you type.

2Open the Extra payments panel and type a monthly amount into Extra every month, or test a once-a-year payment or a one-time lump sum in a chosen month.

PITI section with 1.2% property tax, $1,650 home insurance, $45 HOA and an extra $200 monthly principal payment entered — Add property tax, insurance, PMI and HOA for the true monthly cost, plus any extra payment.

3Read the savings line, which shows the interest saved and how many years and months sooner the loan is paid off, and compare the new payoff date.

Mortgage results: $3,045 monthly payment including a $200 extra payment, $346,500 loan, $320,346 total interest and a July 2050 payoff, with a principal, tax, insurance, PMI and HOA breakdown — The full monthly payment (PITI plus extra), total interest, payoff date and how much the extra payment saves — here $105,964 and 6 years.

4Open the yearly amortization schedule to see how fast the balance drops, then set up the same extra amount as a recurring principal-only payment with your servicer.

Amortization chart of the remaining loan balance falling to zero, above a yearly schedule of principal, interest and balance — The amortization chart and yearly schedule show where every payment goes — export it as CSV.

Common mistakes to avoid

⚠️Sending extra money without marking it principal only, so the servicer holds it as an early payment and no interest is saved.

⚠️Paying a biweekly service a fee for a schedule you could replicate by adding one twelfth of a payment each month.

⚠️Prepaying the mortgage while carrying credit card balances at 20% or more.

⚠️Emptying the emergency fund to make a lump-sum payment, then relying on a card when the car or furnace breaks.

Pro tips

✓Round your payment up to the next hundred dollars; it is painless, and a $2,275 payment rounded to $2,400 adds $125 of principal every month, which trims several years from a 30-year schedule without a noticeable change in your budget.

✓Put raises to work: add half of every pay increase to the extra principal amount.

✓Front-load when you can, because a dollar prepaid in year two saves far more than a dollar prepaid in year twenty.

✓Recheck your PMI status once the balance approaches 80% of the original home value and ask the servicer to remove it.

✓Keep a spreadsheet or screenshot of each year's calculator result so you can see progress and stay motivated.

Frequently asked questions

Is it better to pay extra monthly or one lump sum a year

Money paid sooner saves slightly more, so monthly extra beats the same total paid once in December. The difference is small; consistency matters more than the schedule.

Do extra payments lower my monthly payment

No. They shorten the loan and cut total interest, but the required payment stays the same unless you ask the lender to recast the loan.

Can I stop making extra payments later

Yes. Extra principal is voluntary, so you can pause any month. That flexibility is the main advantage over refinancing into a shorter term.

Should I pay extra on a 3% mortgage

It depends on your alternatives. With a 3% rate, a savings account or investments may earn more, but paying extra still guarantees a 3% return and reduces debt risk.

Does the calculator apply extra from the first month

Yes. The Extra every month amount is added from the first payment; you can also test a once-a-year extra or a one-time lump sum in any month, and the tool reports the interest and PMI saved and the new payoff date.

📌 Bottom line

Extra mortgage payments go straight to principal, so even $100 or $200 a month saves tens of thousands and ends the loan years early; mark every extra dollar principal only, handle high-interest debt and savings first, and let the calculator show your exact new payoff date.

Open the Mortgage Calculator tool →