Extra repayments calculator — see how much you can save

How extra repayments work

Every dollar you pay above your minimum scheduled repayment goes directly to reducing your loan principal. Because Australian home loan interest is calculated daily on your outstanding balance, reducing the principal immediately reduces the interest charged in every future period. This effect compounds over time — the earlier you make extra repayments, the greater the total saving.

How much can you save?

Illustration: $500,000, 5.5% held constant, 25 years, monthly payments and no fees. The Calcy model estimates $421,131 interest with scheduled payments and $301,707 with $500 extra each month. Model interest saving: $119,424; payoff is 75 whole months earlier under this payment schedule.

An extra $500 each month adds $6,000 to the annual payment budget. Savings depend on the outstanding balance, payment timing, future rates and any contract charges.

Lump sum repayments

A one-off lump sum reduces the outstanding balance when applied. Use the calculator’s lump-sum amount and timing inputs to compare the same loan with and without that payment. Confirm permitted extra payments, charges and redraw access before using savings that you may need again.

Fortnightly vs monthly repayments

Half the monthly payment every fortnight totals 13 monthly payments a year, so it requires a larger annual cash budget than 12 monthly payments. A fortnightly amount calculated as monthly × 12 ÷ 26 preserves the annual budget. Check which approach the lender uses; frequency alone does not guarantee a particular saving.

Extra repayments vs offset account

Both reduce the interest you pay. Extra repayments permanently reduce your balance — the money is not easily accessible again. An offset account holds funds separately while offsetting your loan balance for interest calculation, keeping cash fully accessible. The comparison depends on equal balances and timing, the offset percentage, account fees and redraw terms. Confirm these rather than assuming identical savings.

Fixed rate loans and extra repayments

Extra-repayment limits and charges depend on the loan contract. Fixed-rate products may restrict extra repayments or charge break costs; variable-rate products can also have conditions. Confirm your permitted amount, fees and redraw access with the lender before making a payment. The model assumes the entered extra payments are permitted. Compare switching costs in the refinancing guide before changing loans to obtain repayment flexibility.

Compare regular extras in a workbook

Save and compare the no-extra baseline and regular payment scenarios in the free extra repayment and payoff spreadsheet. The custom schedule makes interest and principal visible without uploading your figures.

How much does paying extra save on my mortgage?

Extra repayments can reduce interest and shorten the loan term. Compare your balance, rate and extra payments below; check any fixed-rate limits, fees and break costs with your lender.

How to see the impact of extra mortgage repayments

1. Enter your loan details

   Add the loan amount, interest rate and remaining term.

2. Add your extra repayment

   Type how much extra you'd contribute each month on top of the minimum.

3. Compare the outcomes

   See years saved and total interest avoided versus the baseline schedule.

Frequently asked questions

How much do extra repayments save on a mortgage?

Extra-repayment savings depend on the balance, rate, remaining term and payment timing. For a $500,000 loan, enter those assumptions and compare the standard and accelerated schedules. The model excludes lender penalties unless you account for them separately.

Is it better to make extra repayments weekly or monthly?

Earlier principal reductions can reduce interest. Compare the same total annual extra payment when changing frequency. Calcy spreads the entered annual extra amount across base repayment periods; it does not simulate exact daily posting dates.

Can I make extra repayments on a fixed rate loan?

Extra-payment limits and break costs depend on your fixed-rate contract. Ask your lender before paying more than the scheduled amount. Variable rate loans also have product-specific terms; there is no universal annual dollar allowance.

Should I put extra money into an offset account or make extra repayments?

Both reduce interest. Extra repayments permanently reduce the loan balance — funds aren't easily accessible again. An offset account holds savings separately while offsetting interest, keeping money accessible. If you need flexibility, an offset is generally better; if discipline is the priority, direct extra repayments work just as well.

What is the effect of a lump sum repayment?

A one-off lump sum reduces principal when applied. Its effect depends on the amount, payment date, interest rate and remaining term. Use the lump-sum input to compare schedules and confirm any lender restrictions or fees.

Data sources

RBA Cash Rate — Reserve Bank of Australia — 30 Sep 2026 (checked 14 Oct 2026)

ASIC MoneySmart — Mortgage Calculator Methodology — 2026

ASIC Moneysmart — extra repayments and contract limits — reviewed 16 Oct 2026