What does the extra repayment calculator show?
This calculator compares a principal-and-interest home loan with its standard scheduled repayments against the same loan with an extra amount added every payment period. It estimates interest saved and how much sooner the balance could reach zero.
It is a planning tool, not a lender quote. Both scenarios use the same interest rate and starting balance. You can explore an affordable extra payment without assuming future income or a lower rate.
How to use this calculator
Enter your current loan balance, annual interest rate and remaining term in whole years. Choose monthly, fortnightly or weekly repayments, then enter the extra amount you intend to pay at that frequency.
The default example is a $400,000 loan at an illustrative 6% over 30 years, with $200 extra each month. Valid inputs update automatically. Calculate refreshes the result, and Reset restores this example.
How repayment frequency affects the result
The extra payment applies each time a repayment is made: $200 monthly means $2,400 extra a year, while $200 fortnightly means $5,200 and $200 weekly means $10,400. Check this amount when you switch frequency.
Standard repayments are recalculated over 12, 26 or 52 equal periods per year. Fortnightly payments are not simply half a monthly payment. This prevents an accelerated payment convention from being silently added to your chosen extra amount.
Why extra repayments can save interest
Each payment covers that period’s interest and then reduces principal. Paying extra reduces principal faster, leaving a smaller balance on which future interest is charged. Continuing this pattern can shorten the loan.
The main repayment figure includes your chosen extra amount. The note underneath shows the standard instalment separately. The final payment is reduced to exactly what is needed to clear the remaining loan.
Start with an extra $200 per month
For $400,000 at 6% over 30 years, the standard monthly repayment is approximately $2,398.20. Adding $200 makes the regular planned repayment approximately $2,598.20.
Use the results to see the difference across the full repayment schedules. Try $50, $100 or $500 extra to explore your own budget. These are hypothetical constant-rate scenarios, not advertised product rates.
How interest and time savings are calculated
The standard repayment uses the amortisation formula based on principal, periodic interest rate and number of periods. Each schedule charges interest on the opening balance and subtracts the payment after interest. The extra-payment scenario adds your selected amount to the standard payment.
Interest saved is the difference between total interest in the two schedules. Time saved is the difference in whole payment periods. Calculations retain full precision; displayed amounts and CSV figures are rounded to cents. Actual lenders may calculate daily interest and round payments differently.
Understand the chart and downloadable schedule
The solid blue line shows the standard loan balance. The dashed navy line shows the balance with extra repayments. Move the slider to compare both balances at a selected payment period.
The annual comparison shows year-end balances and cumulative interest savings. Download Schedule exports a CSV with both schedules, including repayments, interest, principal and remaining balances. Entries after the extra-payment loan is repaid show zero further cash flows.
Check your lender’s extra repayment rules
Some loans, particularly fixed-rate loans, restrict extra repayments or apply charges. Check the allowable amount and any fees before making an additional payment. Fees are not included in this estimate and could reduce the benefit.
Also consider whether you need accessible emergency savings. Redraw availability depends on the loan’s terms. An offset account is a different arrangement and is not modelled here.
Assumptions and limitations
The interest rate and extra payment stay constant for the entire calculation. Payments occur at the end of each equal period, starting with the first instalment. The model excludes fees, interest-only periods, missed payments, lump sums, offset balances and redraw.
At 0% interest, extra repayments can shorten the loan but cannot save interest. With no extra repayment, both schedules match. These estimates do not assess affordability or borrowing approval. Confirm repayment arrangements with your lender.
Frequently asked questions
Can I make extra repayments on a fixed-rate loan?
Some fixed-rate loans limit extra repayments or charge fees. Check your lender’s conditions before paying extra. This calculator excludes such fees.
Does the extra amount change when I select weekly repayments?
The entered dollar amount stays the same, but applies every week instead of every month. Adjust it to reflect your intended annual budget.
Does the main repayment include the extra amount?
Yes. The main result combines the standard scheduled repayment with your extra payment. The standard amount is also shown separately.
What if I enter zero extra repayments?
Both schedules match, with no interest or time savings.
Does this include a lump-sum payment?
No. It models a regular extra payment starting with the first instalment, not a one-off lump sum.
Can I download the repayment schedule?
Yes. Download Schedule creates a CSV comparing both scenarios without requiring your contact details.
Will the actual lender result be identical?
Not necessarily. Daily interest, rate changes, fees, payment dates and rounding can affect the lender’s result.
Is the default rate live?
No. The editable 6% rate is an illustration, not a live offer or automatically updated rate.
Find a repayment plan that fits your life.
Talk through the features and costs with Capital Connections. We support clients in Adelaide and through remote appointments across Melbourne, Sydney, Brisbane, Perth, Canberra, Hobart and Darwin.
Further reading: ASIC Moneysmart: pay off your mortgage faster. General estimates only, not financial advice or a lender quote. Confirm fees and product terms. This calculator does not submit your financial inputs.