How to Use a Refinance Calculator (Australia): Break-Even, Costs and Savings

A lower advertised rate is not enough. You need the new repayment, the switching bill, and the month when savings finally cover that bill. This guide shows how to use the refinance calculator for that comparison, then points to the broader refinancing guide for timing and process.

The 30-second summary

• Inputs that matter: current balance, current rate, remaining term, new rate, new term, total switching costs.
• The decision metric is break-even months, not the shiny new repayment alone.
• Formula: total costs ÷ monthly savings = months to break even.
• Watch for term reset (e.g. 22 years left → new 30-year loan) - lower payments can mean more total interest.
• Include discharge fees, application fees, valuation, legal and government charges; add fixed-rate break costs if relevant.
• Recheck LVR so a new LMI premium does not wipe the gain.

What to enter

Input	Why it matters
Current loan balance	Starting principal for the new loan
Current interest rate	Baseline repayment and interest path
Remaining term	Fair comparison if you keep the same horizon
New interest rate	Drives the new repayment
New loan term	Changes both cash flow and lifetime interest
Switching costs	Required for an honest break-even

Pull balance and rate from your latest statement, not memory. Garbage in still produces confident-looking garbage out.

Worked example - $500,000 balance

Item	Current	New offer
Balance	$500,000	$500,000
Rate	6.20% p.a.	5.70% p.a.
Term	25 years remaining	25 years
Monthly repayment (approx.)	$3,288	$3,132
Monthly saving	-	$156
Switching costs	-	$2,500
Break-even	-	≈16 months ($2,500 ÷ $156)

From month 17 onward the $156 is genuine surplus, assuming rates and fees stay as modelled. If you plan to sell in 12 months, this switch loses money even though the rate looks better.

Run the same scenario in the refinance calculator and stress a higher new rate by 0.5-1.0% to see how fragile the saving is.

Reading the outputs together

1. New monthly repayment - immediate cash-flow effect.
2. Total interest difference - the long-horizon prize (or penalty if you stretch the term).
3. Break-even month - when costs are repaid from savings.

A budget-focused household may accept a longer term for lower payments. An aggressive saver should match or shorten remaining term and push extras through the extra repayment calculator or an offset account.

Common traps the calculator catches

• Ignoring fees - a 0.3% cut that takes four years to break even may not suit a near-term sale.
• Term extension - the monthly drop feels like a win while lifetime interest climbs.
• Fresh LMI - LVR above 80% on the new loan can add thousands once.
• Fixed-rate exit - break costs on a fixed loan can dominate the cost line; get a figure from the current lender before modelling.

For when to refinance, discharge fees, break costs and LMI top-up caution in more depth, see the complete refinancing guide.

FAQ

What does a refinance calculator actually compare?

It lines up your current balance, rate and remaining term against a new rate and term, then subtracts switching costs from the projected savings. The useful outputs are the new repayment, total interest difference and months to break even - not just the headline rate cut.

How do I calculate the break-even point?

Divide total refinancing costs by monthly repayment savings. Example: $2,500 costs ÷ $156 monthly saving ≈ 16 months. If you expect to sell or refinance again before that date, the switch may not pay for itself.

Which costs should I include?

Discharge/exit fees from the current lender, application or establishment fees on the new loan, valuation, legal/conveyancing, and state mortgage registration or discharge fees. Fixed-rate break costs can dwarf everything else if you leave a fixed period early.

Can refinancing accidentally cost more interest?

Yes. Resetting a loan with 20 years left to a fresh 30-year term cuts the monthly repayment but can raise total interest sharply. Match or shorten the remaining term unless cash-flow relief is the explicit goal.

What about LMI when I refinance?

If your new LVR sits above 80%, you may face a fresh LMI premium. That can erase years of rate savings. Check current valuation and balance before you assume a clean switch.

How often should I re-run the numbers?

At least once a year, and whenever a fixed term ends, the cash rate moves meaningfully, your equity jumps, or advertised rates sit clearly below yours. Use the refinance calculator with real statement figures, not round guesses.

Next step

Model your current loan against a real offer in the refinance calculator, then read the refinancing guide for process, documents and timing. If rate structure is the open question, see how Australian mortgage rates work.

This article provides general information and does not constitute personal financial advice. Lender fees, break costs and approval criteria vary - confirm figures with your lender or broker before switching.