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Mortgage Overpayment Calculator

Estimate how mortgage overpayments could reduce your monthly interest cost, shorten your term, and lower total interest paid.

Your Details

Overview

Use this mortgage overpayment calculator to see how paying extra each month could affect your mortgage. Enter your remaining balance, interest rate, remaining term, and planned monthly overpayment to estimate your updated payment, interest savings, and time saved.

How it works

The calculator first works out your standard monthly repayment using your mortgage balance, interest rate, and remaining term. It then adds your monthly overpayment and estimates how many months it would take to clear the balance at that higher payment level. The difference between the original and revised totals shows the potential interest saving and term reduction.

How to use this calculator

  1. 1Enter your current mortgage balance.
  2. 2Add your annual interest rate.
  3. 3Enter the number of years left on your mortgage.
  4. 4Type the extra amount you want to overpay each month.
  5. 5Review the estimated payment, interest saved, and reduced term.

Example Calculation

Mortgage balance

$250,000

Annual interest rate

6%

Remaining term

25

Monthly overpayment

$200

Monthly payment with overpayment

$1,735

For a $250,000 mortgage at 5.5% with 25 years remaining, paying an extra $200 a month could shorten the term by several years and reduce the total interest paid by tens of thousands of dollars.

Frequently asked questions

What does this mortgage overpayment calculator estimate?

It estimates your regular mortgage payment, your payment after overpaying, the interest you could save, and how much sooner you may repay the mortgage.

Does overpaying always reduce the mortgage term?

In many cases it can reduce the term, total interest, or both, but the exact effect depends on how your lender applies overpayments.

Can I use this for a fixed or variable mortgage?

You can use it for either as a simple estimate, but the result assumes the interest rate stays the same over the remaining term.

Why might my lender's figures be different?

Lenders may use different rounding rules, daily interest calculations, fees, or overpayment rules that change the final numbers.

Should I check for early repayment charges?

Yes. Some mortgages limit overpayments or charge fees if you repay too much too soon, so it is worth checking your mortgage terms first.

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Assumptions and warnings

Assumptions

  • This calculator assumes a standard repayment mortgage with a fixed interest rate over the remaining term.
  • Overpayments are assumed to be made every month and applied directly to the mortgage balance.
  • The estimate does not include lender fees, early repayment charges, offset features, or payment holidays.
  • Results are estimates and small differences may occur due to lender calculation methods and rounding.

Warnings

  • This calculator provides an estimate only and is not financial advice.
  • Check whether your lender charges early repayment fees or limits overpayments before making extra payments.