Affordability calculator
Free, no sign-up, runs in your browser.
Eligibility asks how much you can borrow; affordability asks what you can buy, which is the loan plus the cash you bring. The two diverge because the deposit does double duty: it adds to the price directly, and it has to satisfy the lender's loan-to-value ceiling on whatever you choose.
The formula
Price = the loan your income supports + your down payment, capped by deposit ÷ (1 − loan-to-value). With an eighty per cent ceiling, a deposit must cover a fifth of the price, so the deposit alone limits you to five times what you have saved.
A worked example
A $250,000 loan at 8.75% over 20 years:
| Monthly instalment | $2,209 |
|---|---|
| Total interest | $280,225 |
| Total repaid | $530,225 |
| Interest vs loan | 112% |
| Interest in month 1 | $1,823 |
| Interest in the final month | $16 |
What to watch
- Stamp duty, registration and legal fees are rarely lendable, so they come straight out of the deposit and reduce the price you can reach.
- The deposit often binds before income does. Earning more does not help if the lender will only fund eighty per cent of the purchase.
- What you can borrow and what you can comfortably repay are different questions. Lenders approve to their limit, not to yours.
- Budget for the running costs the lender ignores — maintenance, insurance, property tax — before spending to the ceiling.
The trap
Spending the whole deposit on the purchase price and leaving nothing for the fees, which then have to come from somewhere less convenient at the worst moment.
Questions
How much house can I afford?
The lesser of two figures: the loan your income supports plus your deposit, and your deposit divided by the share the lender will not fund. The calculator shows both and names which one is holding you back.
How big a deposit do I need?
Enough to cover the gap above the loan-to-value ceiling, plus the fees. At an eighty per cent ceiling that is twenty per cent of the price before fees — and the fees frequently add several per cent more.
Should I borrow the maximum I am offered?
Rarely. The lender's limit is set by what you can service, not by what leaves you room for a rate rise, a repair, or a quiet month. Running the numbers one band lower is usually the more useful exercise.
Rate bands and lending rules on this page were last reviewed on 2026-10-23 and are indicative, not offers. The arithmetic is produced by the same code the calculator runs. Confirm the terms with your own lender before committing; nothing here is financial advice.