Australian mortgage & home-finance calculators

What makes an Australian mortgage different

Australia sits between the British and American models and has two features neither shares.

Variable rates are the norm, not the exception. Most Australian borrowers are on a variable rate that moves with the RBA cash rate, or on a short fix of one to three years. There is no equivalent of the American 30-year fixed, so a rate rise reaches an Australian borrower within a month or two rather than at the end of a term.

You are assessed at a rate three percentage points above the one you will pay. APRA requires authorised deposit-taking institutions to apply a serviceability buffer of at least 3.0% over the loan's interest rate. This is binding under Attachment C of Prudential Standard APS 220, with guidance in APG 223, and it was raised from 2.5% in October 2021. So a loan quoted at 6% is assessed as though you were paying 9%, which is the single largest constraint on what you can borrow.

Lenders Mortgage Insurance applies below 20% deposit, protects the lender, is paid by you, and is usually capitalised into the loan. Like Canada's CMHC and unlike US PMI, it does not fall away when your equity crosses a threshold.

Repayments are often weekly or fortnightly rather than monthly. That is not only a convenience. Twenty-six fortnightly payments amount to thirteen monthly payments a year rather than twelve, so a borrower paying fortnightly is making an extra month's payment annually without noticing, and clearing the loan earlier as a result.

Stamp duty is a state tax, and the differences are large

There is no national stamp duty. Each state and territory sets its own rates, bands, thresholds and concessions, so the same purchase price produces materially different duty in New South Wales, Victoria, Queensland and Western Australia.

First-home-buyer concessions differ by state too, with their own price caps, and several states apply a surcharge to foreign purchasers. This is why a single Australian figure does not exist and why the calculator asks for your state before returning anything.

Offset accounts, and why they are used differently here

An offset account is a transaction account whose balance is deducted from your loan balance for interest purposes. Money in it reduces the interest you pay while remaining available to withdraw, which is the distinction from an overpayment.

For an Australian owner-occupier that is a straightforward saving. For an investor it interacts with negative gearing, since mortgage interest on an investment property is deductible while interest on an owner-occupied one is not. That asymmetry is why offset arrangements are structured carefully here and why generic advice from other markets does not transfer.

What the rate follows

Variable rates follow the Reserve Bank of Australia cash rate, though lenders pass changes through at their own pace and not always in full. Short fixes are priced off swap rates and move on expectations rather than on decisions.

Where the calculators fit

The borrowing power calculator applies the APRA 3.0% serviceability buffer and the Household Expenditure Measure floor, because both bind before your income does. The stamp duty calculator holds each state's bands and concessions, checked against the state revenue office and dated. The repayment calculator supports weekly, fortnightly and monthly schedules, since the choice changes the payoff date. The LMI calculator gives the premium by deposit size.

Every figure is computed from the underlying formula rather than repeated from another site, and every statutory value carries the date it was last verified against the primary source.