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Early Repayment Savings Calculator

Calculate interest saved by making early or overpayments on your mortgage or loan. See how extra payments reduce your balance and shorten your repayment term.

Last reviewed 15 August 2026

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Calculator inputs

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When to use this calculator

  • Before comparing mortgage products, brokers or repayment types.
  • When you want to test how a different deposit, rate or term changes the payment.
  • When you need a quick estimate before using a formal illustration or agreement in principle.
  • When you are stress-testing your budget against a higher rate.

A realistic Australia planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

A realistic Australia planning example
InputValue
Loan Amount (A$)A$560,000
Interest Rate (%)5%
Original Term (Years)25 years
New Term (Years)25 years

After entering these figures, review interest saved and new monthly together rather than in isolation. Then rerun the tool with one input adjusted.

How to read your results

Interest Saved

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

New Monthly

The figure produced by this output for the inputs you entered. Change one variable at a time if you want to see what drives it.

Method & assumptionsAuthoritative sources

This calculator models the effect of making one or more overpayments on a standard capital repayment mortgage. It recalculates the full amortisation schedule from the point of each overpayment, showing how the reduction in principal leads to lower interest charges in every subsequent month. The interest saving figure represents the cumulative difference between the original schedule and the revised one. The calculation assumes the interest rate remains constant throughout the remaining term, which will not be the case if you are on a tracker or variable rate product. It also assumes the lender applies the overpayment immediately to the principal rather than holding it in a suspense account — practices vary, so confirm the arrangement with your lender.

Common mistakes

  • !Mixing up loan amount and property value, which distorts affordability and LTV.
  • !Using a headline rate but forgetting fees, insurance or repayment type.
  • !Testing only one term length instead of comparing payment and total cost together.
  • !Treating the result as a lender decision rather than a planning estimate.

What to do next

  • Run a second scenario with a cautious assumption so you can see the downside clearly.
  • Compare the result with the related calculators below before making a decision.
  • Check current local rules, eligibility and provider terms before applying or committing money.
  • Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.

Frequently asked

Most UK fixed-rate mortgages allow overpayments of up to 10% of the outstanding balance per calendar year without triggering an early repayment charge. Variable and tracker mortgages are usually unlimited. Check your offer document for the exact allowance as some lenders measure against the original balance instead.

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