Home/Calculators/Mortgage
05 of 18Borrowing
Mortgage Calculator
Australian mortgages are usually 25 to 30 years, and the difference between a good structure and a poor one is measured in six figures. Start with the repayment, then look at what the structure costs.
Weekly, fortnightly or monthly · Extra repayments modelled
At a glance
Interactive calculator
Live — results update as you type
Your loan
Australian loans are usually quoted as a comparison rate — use that.
Repayment
$0per month
—
What actually moves the number
The rate, first
On a $750,000 loan over 30 years, half a percentage point is worth $85,965 in interest. It is the largest single lever and the only one you can renegotiate this week.
Frequency, second
Paying fortnightly instead of monthly gives you 26 half-payments, which is one extra monthly repayment a year. On this loan that is $189,339 of interest.
Extra repayments, third
An extra $250 a month on the same loan saves $135,202. Nothing else in a household budget returns that reliably, and it is reversible if your circumstances change.
$750,000 at 6.05% over 30 years
Principal and interest is $4,521 a month, and total interest across the term is $877,476 — more than you borrowed.
Three structural changes, priced by the calculator: adding $250 a month saves $135,202 and clears the loan years earlier; switching to fortnightly saves $189,339; finding a rate half a point lower saves $85,965. The rate is the biggest lever, and it is the one you can renegotiate tomorrow.
Australian mortgage questions
What is a comparison rate and why does it matter?
The comparison rate folds the interest rate and most upfront and ongoing fees into one number, calculated on a standard $150,000 loan over 25 years. It is the only honest way to compare two loans. A 5.99% rate with a $1,500 annual fee is not cheaper than a 6.19% rate with no fee.
How much deposit do I need in Australia?
Twenty per cent avoids Lenders Mortgage Insurance entirely. Between 10% and 20% you will usually pay LMI, which can run to $15,000 or more on a typical Sydney or Melbourne loan. Below 10% deposit, fewer lenders will consider the application.
Fixed, variable or split?
Fixed gives certainty on repayments and removes offset functionality in most cases. Variable keeps flexibility and offset access. Split does both, at the cost of admin complexity. The right answer depends on whether your risk is the repayment or the flexibility.
Does an offset account beat extra repayments?
An offset reduces interest identically while keeping the money accessible, and it is not taxed. Extra repayments into the loan are harder to withdraw and, on some fixed products, locked. For most households with spare cash, the offset is the better structure.
What is the serviceability buffer?
APRA requires lenders to assess your application at your rate plus 3 percentage points. At a 6% actual rate, you are assessed at 9%. That buffer, not the actual repayment, is what usually limits borrowing capacity.
More calculators
Turn these numbers into a decision
A calculator gives you a range. An adviser gives you a decision — pressure-tested against your super, your tax position and the life you actually want to fund.
General advice only · No obligation · No product push
Repayments are calculated on a constant interest rate for the full term. Actual loans have rate changes, fees and charges not modelled here. Lenders assess applications against a serviceability buffer. General information only — not a credit quote or approval.
Reviewed November 2026 · FY2026–27 rates and thresholds