Legacy Investing CalculatorsShow

Mortgage extra payment

How much time and interest can overpayments save?

Your numbers

$
%
yrs
$

Interest saved

$112,235

Time saved6 yrs 10 mo
New payoff time20 yrs 2 mo
Scheduled payoff time27 yrs
Payment with extra$2,528.89
Interest without the extra$382,159

Tip. Confirm the servicer applies extras to principal rather than banking them as an advance payment.

Assumptions

  • The extra amount goes to principal every month on top of the scheduled payment.
  • Rate and scheduled payment stay fixed for the rest of the term.
  • Escrow for tax and insurance is excluded, so the payment shown is principal and interest only.

Sources

  • Freddie Mac Primary Mortgage Market Survey, mid-2026

Explore the numbers

Examples and charts

Start with a scenario, then read the response curve to see which input actually moves the answer.

Example 1

A modest extra

Around $100 a month, which still moves the payoff date by years.

Interest saved

$47,714

Example 2

Meaningful extra

$300 a month toward principal on a large balance.

Interest saved

$112,235

Example 3

Biweekly equivalent

Roughly one extra payment a year, spread monthly, which is what biweekly schedules actually do.

Interest saved

$77,279

Sweeps extra monthly payment from half to one and a half times your value, holding everything else fixed.

Response curve

How extra monthly payment moves the result

Interest saved

$112,235

$80k$100k$120k$140k$200$300$400
Chart axis: Extra monthly paymentNow $300$112k

Timeline

How much sooner the mortgage clears
$0$100k$200k$300kStartY13Y27
  • Balance with extra payment
  • Balance on schedule

What this calculates

Shows how a fixed monthly extra toward principal shortens the loan and cuts interest. The two balance curves make the time saved visible rather than abstract.

How to use it

  1. Start with loan balance and work down the form, or load an example to begin from a realistic case.
  2. Read the headline result alongside the supporting rows, which show the intermediate figures behind it.
  3. Check the assumptions. They decide what the number includes and, more importantly, what it leaves out.
  4. Sweep extra monthly payment on the response curve to see how much it actually moves the answer.
  5. Run a cautious case as well as an optimistic one before using the estimate in a decision.

Common mistakes

  • Paying extra on a mortgage while carrying credit card debt at three times the rate.
  • Assuming the servicer applied the extra to principal without checking the next statement.
  • Draining the emergency fund into home equity, which is expensive to get back out.

Formula

Amortize with payment = scheduled payment + extra

Inputs

  • Loan balance
  • Rate (%)
  • Remaining term (yrs)
  • Extra monthly payment

FAQ

What about biweekly payments instead?

A biweekly schedule produces 26 half-payments a year, which is 13 monthly payments rather than 12. Divide your monthly payment by 12 and enter that here to approximate the same effect without paying a service to set it up.

Why do early extras matter more than late ones?

Interest is charged on the outstanding balance. A dollar of principal removed in year two avoids interest for twenty-five years; the same dollar in year twenty-five avoids almost none.

Does paying extra lower my monthly payment?

No. It shortens the term instead. Reducing the payment requires a recast, which some servicers offer for a fee, or a refinance.

Should I pay extra or invest?

The mortgage versus index investing calculator frames that trade directly. Paying down a mortgage is a guaranteed return at your rate, and investing is a higher expected return with real risk.

How much does an extra $100 a month save on a mortgage?

On a 30-year, $300,000 loan at 6.5%, an extra $100 a month cuts about four years off the term and saves roughly $60,000 in interest. The earlier you start, the larger the saving.

Does paying extra lower my monthly payment?

No. Extra payments shorten the term and reduce total interest, but the scheduled payment stays the same unless you recast or refinance the loan.

What is a mortgage recast?

A recast re-amortizes the remaining balance over the original term after a lump-sum payment, lowering the monthly payment for a small fee. It suits people who want a lower payment rather than a shorter term, and it does not change the rate.

Should I make extra mortgage payments or save the money?

Compare the mortgage rate with what a safe investment reliably returns. Paying down a loan above that bar is a guaranteed return at the mortgage rate; keep an emergency fund and retirement match first.

Are these numbers financial advice?

No. They are educational estimates based on the inputs and assumptions on this page. Confirm important decisions with a qualified professional and your own documents.

Read the full guideShould you pay off your mortgage early?

The questions people usually ask next.