Australia Mortgage refinance calculator

Compare your current loan against a refinance to see break-even point and lifetime savings.

By Ward Last reviewed 26 May 2026 Methodology

Current loan

Remaining balance (AUD)Current rate (% APR)Years remaining on current loan

New loan

New rate (% APR)New term (years)Closing costs (AUD)

Monthly saving

$336.07

Break-even

17.9 months (1.5 yrs)

Comparison

	Current	New
Monthly payment	$1,925.88	$1,589.81
Remaining interest	$343,985.71	$292,331.31

Lifetime saving (after closing costs)

$45,654.39

Total interest saved over the full loan life, minus what you pay in closing costs. Negative means refinancing costs you more over the long run â€” but you may still benefit from lower monthly payments.

Want the full picture? Should I Refinance My Mortgage? →

How a refinance break-even is calculated

The break-even point of a refinance is the number of months it takes for your reduced payment to recoup the upfront closing costs:

Break-even months = closing costs ÷ monthly savings

If a refinance costs $4,800 and saves $200/month, you break even at 24 months. After that point, every additional month is pure saving; before it, you've lost money relative to keeping the existing loan.

Worked example

Current mortgage: $300,000 balance at 7.5% over 30 years remaining → $2,098/month
New mortgage: $300,000 at 6.0% over 30 years → $1,799/month
Closing costs: $5,000
Monthly savings: $299
Break-even: $5,000 ÷ $299 = 16.7 months
Lifetime interest saved if you stay the full new term: ~$107,700

When refinancing makes sense

Two conditions must hold: (1) your monthly savings × months you'll stay in the home must exceed closing costs, and (2) the lifetime interest savings should be material enough to make the paperwork worthwhile. A rough rule of thumb is a rate drop of 0.5–0.75 percentage points combined with 3+ more years in the home.

The "reset the clock" trap

Refinancing from a 30-year mortgage you're 5 years into, into a fresh 30-year mortgage, means paying interest for 35 total years on the property. Lower monthly payment, but potentially more lifetime interest. Two ways to avoid this: refinance to a 15- or 20-year term, or keep the new mortgage but pay extra each month to mimic the old payoff schedule.

Common mistakes

Looking only at the monthly payment delta. A lower payment achieved by extending the term may cost more in lifetime interest.
Forgetting the time horizon. Closing costs matter only if you'll stay long enough to recoup them.
Ignoring opportunity cost of the closing costs. $5,000 invested at 7% for 25 years grows to about $27,000.
Skipping the rate-lock window. Rates can move 0.25–0.50 percentage points in a week. Always lock once committed.

What this calculator doesn't cover

Cash-out refinance (additional principal beyond the existing balance)
ARM-to-fixed conversions with rate-cap modelling
Tax treatment of mortgage interest deduction differences
Specific points/buy-down economics

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Frequently asked questions

When does refinancing make sense?

Refinancing makes sense when your monthly savings will cover closing costs within the time you expect to stay in the home. A rough rule of thumb: a rate drop of 0.5–0.75 percentage points usually pays off if you'll stay 3+ years. Lifetime interest savings can run into tens of thousands even at smaller rate differentials.

How do I calculate the refinance break-even point?

Divide total closing costs by monthly payment savings. If a refi costs $4,800 and saves $200/month, you break even after 24 months. Stay past that point and refinancing is net positive; sell or refinance again before, and you lost money. The calculator above shows your break-even month and lifetime saving automatically.

Are refinancing closing costs tax-deductible?

In the US, points paid to lower the rate are generally amortized over the life of the new loan rather than deducted in the year paid — different from a purchase mortgage. Other closing costs (appraisal, title, origination) are generally not deductible. Rules vary by market and change over time; check official guidance or a tax professional.

Does refinancing hurt my credit score?

Yes, slightly and temporarily. The hard credit pull typically drops your score by 5–10 points and the new account lowers your average account age. Multiple mortgage inquiries within 14–45 days usually count as a single pull. Scores normally recover within 6–12 months as the new account ages.

Should I refinance to a 15-year mortgage?

A 15-year refi can dramatically cut total interest — often 50%+ — and 15-year rates are usually 0.25–0.5 percentage points lower than 30-year. The trade-off is a higher monthly payment. If you'd otherwise prepay aggressively on a 30-year anyway, the 15-year locks in the discipline and the better rate.

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