Refinance calculator
Put in what you owe, your current rate, the years left on your loan, the rate you've been offered and what the switch will cost. The calculator shows your new repayment, the monthly saving, and how many months it takes for the saving to pay back the cost of moving. It compares on the years you have left, not a fresh 30-year loan, so the saving it shows is the real one.
Work out your break-even
Other debts to roll into the new loan (optional)
Debt 1
Debt 2
Debt 3
Debt 4
Darren Parker, Credit Representative 501592, authorised under Australian Credit Licence 389328. This is general information, not credit assistance.
The three numbers it gives you
The new repayment. What you'd pay each month at the offered rate, over the same years you have left. Not stretched back to 30 years.
The monthly saving. Your current repayment less the new one. This is the saving from the rate alone, because the term hasn't changed.
The break-even. How long the monthly saving takes to repay what the switch cost you. Before that month, you're behind; after it, you're ahead.
Why other calculators show a bigger saving
Most refinance calculators put the new loan on a fresh 30-year term. If your loan has 22 years left, stretching it to 30 lowers the repayment on its own, before the rate does anything, and the calculator counts that as saving.
An illustration, not a quote: $500,000 owed, 22 years left, moving from 6.5% to 6.0%. On the same 22 years, the repayment falls from about $3,565 to about $3,415, a real saving of about $149 a month. Put the new loan on 30 years and the repayment drops to about $2,998, which looks like $567 a month. But you'd pay about $579,000 in interest over the 30 years, against about $441,000 if you'd stayed where you were. The lower payment costs you about $138,000.
Put the cost of switching in
A break-even without the costs isn't a break-even. Count what your current lender charges to discharge the loan, the new lender's application and valuation fees if any, the government fees to register the change, and any break cost if you're on a fixed rate. Your current lender can tell you its discharge fee and any break cost; the new one can tell you its fees.
On the example above, with $1,500 of costs, the $149 monthly saving pays them back in 11 months. With a fixed-rate break cost of several thousand, the same switch could take years.
When the answer is to stay where you are
The break-even runs past when you'd move or sell. If you're likely to sell or switch again before the costs are paid back, you're behind.
A fixed-rate break cost is bigger than the saving. The calculator shows this when the break-even stretches out.
Few years left, or a small balance. The saving each month is small, so fixed costs take a long time to recover.
The new rate isn't lower. The calculator says "No break-even" when the offered rate is the same or higher.
Ask your own lender first
Before anything else, many borrowers ring their current lender, quote the rate they've been offered elsewhere, and ask whether it will reprice the loan. There's no application, no valuation and no switching cost, so if the lender matches or gets close, the break-even is immediate. If it won't, you've lost nothing and you have the figures for the calculator.
Rolling other debts into the loan
The calculator can also add up to four other debts, such as a car loan or a credit card, and show the interest both ways: kept separate, and rolled into the home loan. A lower rate isn't the whole story, because the home loan spreads the debt over far more years.
An illustration: a $30,000 car loan at 9% over 5 years costs about $7,400 in interest. Rolled into a home loan at 6% with 22 years left, the same $30,000 costs about $24,100 in interest, unless you pay it off faster. The monthly repayment is lower; the total is higher. The calculator shows which way your own debts go.
If you'll keep money in an offset
Add the balance you'd hold in an offset account after the switch, and the calculator shows how much sooner the loan is paid off and the interest saved, on the new rate and your remaining term. It assumes the offset balance stays the same for the whole loan.
What the calculator doesn't know
It's arithmetic on the figures you put in, not a lender's assessment and not an offer. It doesn't know whether a lender will approve you, what rate you'd actually be offered on your file, or what your current lender would do if you asked. And it only counts the costs you enter.
Refinance calculator questions
Compare your current repayment with the new one over the same years you have left, then divide what the switch costs by the monthly saving. That's the number of months to break even. If you'll keep the loan longer than that, the switch pays for itself.
Want the switch checked properly?
Send me your balance, your current rate, the years left, and any other debts you're thinking of rolling in. I'll check the comparison against what lenders are actually offering for a file like yours, with every cost of moving in it, and tell you if the answer is to stay put.
You'll hear back within the hour in business hours, and by 9am the next business day after hours.
Updated 2 October 2026