The Lenders use two key determinants when looking at how much you can borrow: Your Loan Deposit and your income (also known as your servicing capacity). Assuming you have enough deposit to qualify for a loan, the Lender will look at how much you earn and therefore how much you can afford in repayments. This calculation also takes into account any current debt (including credit cards), how many children or dependents you have, and any other ongoing commitments you may have (ie Health Insurance).
I have access to the borrowing capacity calculators of over 30 lenders and can calculate which lender will suit your needs. You can also calculate your loan repayments if you wish to consider your own budgeting requirements. Pre-approval may also help determine which lender will be the most suitable. This may provide some confidence when negotiating on your new property.