How to use the home loan extra repayment calculator
- Enter your loan amount (or current balance), interest rate, remaining term, repayment frequency and start date.
- Enter an extra amount to pay with every repayment.
- Optionally add a one-off lump sum, such as a tax refund or bonus, and the date you will pay it.
- Compare the payoff dates, interest and balance chart with and without the extras.
Worked example
$500,000 at 6.00% over 30 years, fortnightly, $100 extra and a $10,000 lump sum
Starting 1 October 2026, the scheduled fortnightly repayment is $1,382.92. Adding $100 a fortnight plus a $10,000 lump sum on 1 October 2027 cuts total interest from $570,809.96 to $432,724.15, saving $138,085.81. The payoff date moves from 15 June 2056 to 18 August 2050, about 5 years 10 months sooner.
How it works
Both loans are simulated day by day with the same scheduled repayment: the true monthly, fortnightly or weekly amount that repays the loan over the term. Interest accrues daily on the balance at the rate รท 365 and is added monthly. Extra repayments are paid with each scheduled repayment and the lump sum on its date, reducing the balance immediately. Interest saved and time saved are the differences between the two simulations.
Assumptions
- The interest rate stays constant for the whole loan.
- Your loan allows unlimited extra repayments without fees. Fixed-rate loans often cap extras.
- Extra repayments stay in the loan. If you redraw them, the saving is smaller.
Frequently asked questions
Are extra repayments worth it on a variable loan?
Every extra dollar reduces the balance that interest is charged on, so the saving compounds over the remaining term. The earlier you pay, the more you save.
Can I get my extra repayments back?
Many variable loans have a redraw facility that lets you withdraw extra repayments, sometimes with a fee or minimum. An offset account gives similar interest savings with easier access.
What about fixed-rate loans?
Lenders often limit extra repayments on fixed loans (for example to a set amount per year) and may charge break costs above that. Check your loan terms first.
Limitations
- Does not model rate changes, fees or redraw.
- A lump sum dated after the loan is repaid has no effect.