How repayments are calculated
Lenders use standard amortisation: each repayment covers that month's interest first, and whatever remains reduces the principal. Early on, most of your money is interest — on a $600,000 loan at 6% over 30 years, the repayment is about $3,597 a month and the total interest bill is roughly $695,000, more than the amount borrowed. That lopsidedness is also why the levers below work so well.
The three levers that actually matter
Extra repayments attack the principal directly, and because interest compounds monthly, small amounts punch far above their weight — run $500 extra on the example above and watch years fall off the term. An offset account does the same job with flexibility: every dollar sitting in offset is a dollar not accruing interest, while staying available. The rate itself — when comparing loans, use the comparison rate (which folds in fees), not the headline rate; a 0.25% difference on $600,000 is about $90 a month, every month, for decades. Refinancing quotes are free and loyalty is expensive.
Buying? Repayments are only part of it
Stamp duty is the other big number, and it varies wildly by state — use our stamp duty calculators below to see the full upfront cost before you commit to a deposit size.