Mortgage Switching Calculator
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Results are indicative only and do not constitute financial advice.
Get a personalised resultA lower rate is not the same as a saving
A switching calculator compares two repayments. What decides whether switching is actually worth it is the gap between those repayments and the cost of moving, and how long you stay in the new loan.
The costs fall into predictable categories, even though the amounts differ by lender and by state:
- Discharge or exit administration on the loan you are leaving.
- Application, settlement or establishment fees on the loan you are joining. Sometimes waived, sometimes not, and often the thing a cashback offer is quietly covering.
- Valuation. Whether it is charged, and whether it is a full valuation or a desktop one, is lender policy.
- Government registration and mortgage fees. Set by the state land titles office, not by the lender.
- Break costs, if you are leaving a fixed rate. These are not a fixed penalty. They depend on the lender's funding position and the time left on the fixed term, and they can be large enough on their own to make switching uneconomic.
Ask for the break cost figure in writing before you decide anything. It is the one number in this list that can change the answer completely, and it is only valid on the day it is quoted.
The loan term reset that calculators hide
This is the single most common way a switch that looks like a saving is not one.
If you are eight years into a 30-year loan and you refinance to a new 30-year term, your repayment drops partly because of the lower rate and partly because you have stretched the remaining balance back over three decades. The monthly figure improves. The total interest over the life of the loan can still go up.
The comparison worth making is not old repayment against new repayment. It is total cost to the same end date. If you switch, you can usually ask for the new loan to be written over the remaining term rather than a fresh 30 years, which keeps the comparison honest.
Two things that can stop a switch outright
Not enough equity
Refinancing is a new loan application against a new valuation. If the valuation comes in lower than you expect and your remaining balance is above 80 per cent of it, you can be up for Lenders Mortgage Insurance again on the new loan, even though you paid it the first time. LMI is not transferable between lenders.
Serviceability, reassessed from scratch
A refinance is assessed the way a new purchase is. Your income, expenses and existing commitments are all reassessed under current policy, not the policy that applied when you first borrowed. If your circumstances have changed, or if lender policy has tightened since, the new lender can decline a loan that is smaller than the one you are already paying.
Worth reading before you switch
Why a lender's number will differ from this estimate
A calculator works from the rate you enter. A lender does not.
Lenders regulated by APRA must assess your ability to repay at an interest rate at least three percentage points above the rate you would actually pay, a buffer APRA confirmed on 28 May 2026. That alone is usually why an approval lands below the figure a repayment estimate suggests.
Since February 2026 there is a second constraint: lenders must keep new lending at a debt-to-income ratio of six times income or above to no more than 20 per cent of their new mortgage lending each quarter. It is a quota on the lender rather than a cap on you, but it can decide whether a particular lender wants the application at all.
Current as at 28 August 2026. Reviewed quarterly, or sooner if APRA changes its settings.
Now compare the two loans you are choosing between
The calculator above answers whether moving is worth it at all. This one answers the question that comes next: of the two offers in front of you, which is actually cheaper once the revert rate and the fees are counted.
They are different questions, and the second one catches people out more often, because the loan with the better headline rate is frequently not the cheaper loan.
Loan Comparison Calculator
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Why the headline rate is the wrong thing to compare
The loan with the lowest advertised rate is frequently not the cheapest loan. Three things decide the answer, and only one of them is on the billboard.
- What the rate reverts to, and when. An introductory rate applies for a fixed period. What matters far more is the rate you pay for the remaining twenty-eight years.
- Ongoing fees. A $10 monthly fee is $3,600 over thirty years. That is often larger than the difference the intro rate makes.
- Upfront costs. Application, valuation and settlement fees are paid once, but they are real money and they belong in the comparison.
The default figures above illustrate the trap deliberately. Loan A looks better on the headline: a lower intro rate for two years. Loan B has no intro rate, no upfront fee and no monthly fee, and over the full term it wins comfortably. Change the numbers to the two loans you are actually weighing up.
What this calculator assumes
- The repayment during the intro period is amortised over the full term, not over the intro period. That is how these loans are written: you pay a lower rate on the same schedule, you do not pay the loan off faster.
- At revert, the repayment is recalculated on the balance that remains, at the revert rate, over the remaining term.
- Rates are assumed to hold for the whole term. A variable rate will not, so treat a thirty year total as a way of ranking two loans against each other rather than as a forecast.
- Repayments are monthly and fees are not capitalised into the balance.
Not included: LMI, stamp duty, offset or redraw benefits, and cashback offers. A cashback is worth including in your own arithmetic as a reduction in upfront cost, but check what it is buying: a retention offer is often not the win it appears to be.
Related: the loan repayment calculator.