How to set a buying budget you'll actually stick to

A buying budget you'll actually stick to isn't the biggest number a lender will hand you. It's the number you can live with comfortably once the deposit, the costs and a safety buffer are all accounted for, and after a rate rise or a quiet patch at work.

It's easy to start with the lender's maximum and work backwards. A better starting point is what you can comfortably afford once the full cost of buying and owning the property is taken into account.

This guide frames how to set a budget that holds: why borrowing capacity and purchase price are different things, how to include every cost rather than just the price, how to stress-test the number so it survives contact with reality, and how to hold the line when the pressure is on. The specifics live in the explainers below. Here we give you the framework to hang them on.

Key takeaways

• What you can borrow isn't what you can afford: borrowing capacity, maximum purchase price and the budget you're comfortable with are three different numbers, and a lender's maximum is not a recommendation about what you should spend.
• Budget for the whole purchase: price plus transfer duty where applicable, conveyancing, inspections, lender and registration fees, any loan costs that apply, and moving costs.
• Stress-test the repayments: model your mortgage at several higher interest rates, not just today's rate. There is no single increase that suits every household.
• The 30% rule is a flag, not a target: keeping housing costs under 30% of gross income is a useful sanity check, not a law.
• Decide your ceiling before the day: a written limit set before the auction is easier to stick to than a number you are still deciding in the moment.

1. Borrowing capacity is not your budget

The first mistake is treating the lender's approval as the budget. Borrowing close to your maximum can leave less room for rate changes, unexpected costs or changes in your circumstances.

Three numbers to keep separate

• Borrowing capacity: what a lender may be prepared to lend, based on its assessment.
• Maximum purchase price: the highest property price your available deposit, borrowing and transaction costs may allow.
• Your comfortable budget: the amount you actually decide you're willing to spend, after considering repayments, other commitments, future costs and the financial buffer you want to keep.

These numbers can be very different. A lender's maximum is not a recommendation about what you should spend.

Maximum purchase price isn't one objectively calculable figure either. It is affected by your deposit or equity, your borrowing capacity, the costs of buying, your lender's requirements, the property's valuation, the cash you have available and the buffer you choose to keep.

The explainer on borrowing capacity versus purchase price shows how to work back from the loan to a price you can genuinely sustain. Pre-approval tells you what you may be able to borrow; budgeting tells you what you're actually comfortable spending. See getting pre-approved.

2. Build the budget from all the costs, not just the price

A budget built on the purchase price alone is always too optimistic, because the price is only part of what you hand over. A realistic budget should consider transfer duty where applicable, conveyancing, inspections, lender and registration fees, any lender's mortgage insurance or other loan costs that apply, moving costs and the ongoing costs of owning the property. Some of these costs can be significant, so leaving them out can make your budget look more comfortable than it really is. The explainer on budgeting for all the costs lists each item; for the full cost picture, the real cost of buying a home guide pulls it together.

3. Stress-test and sanity-check the number

Once you have a figure, pressure-test it before you trust it. Two simple checks do most of the work:

• Stress-test the rate: model your mortgage repayments at several higher interest rates, not just today's rate. There is no single increase that suits every household, so use scenarios that reflect your own circumstances and risk tolerance. Your lender's assessment answers whether you may qualify for the loan. Your own budget needs to answer whether you are comfortable carrying it. If the higher number is uncomfortable, that's your signal to borrow less.
• Use the 30% rule as a flag: the old guide of keeping housing costs under 30% of gross income is a useful sanity check, not a hard limit. Treat it as a flag that prompts a closer look at your other commitments and lifestyle, not a target to aim for or a ceiling to max out. Use your actual household budget as the main test, not a percentage by itself.

See the stress-test explainer for how to run the numbers, and the 30% rule explainer for where the old guide still helps and where it doesn't.

4. Holding the line, and what to do if nothing fits

A budget only works if it survives the moment of temptation. The classic trap is auction day, where the number in your head drifts upward one bid at a time. Watch for these:

• No fixed ceiling: set your ceiling before the auction and, if useful, tell someone who can help you stick to it, so it isn't just a number you can quietly revise.
• Auction pressure: bidding can make it harder to stick to a number you decided calmly beforehand. Set your ceiling before the auction starts and treat it as a decision you've already made, rather than something to renegotiate with yourself bid by bid.
• "Just a bit more": small stretches feel harmless in the moment and reshape your whole repayment reality afterwards.
• Nothing in budget: if genuinely nothing fits, the honest levers are to widen your search area, adjust the property type, or save longer, before simply increasing the budget.

The explainer on sticking to your budget at auction covers holding your nerve on the day, and what to do if you can't find anything in budget works through the real options when the numbers won't meet.

Common questions

How do I set a realistic property budget?

Start with what you can comfortably afford, not the maximum a lender may be prepared to lend. Account for your deposit, buying costs, ongoing ownership costs and a financial buffer, then test the repayments against less favourable circumstances.

Is borrowing capacity the same as purchase price?

No. Borrowing capacity is one input. Your purchase price also depends on your deposit, the costs of buying and the funds you have available.

Should I spend my maximum borrowing capacity?

Not necessarily. Borrowing capacity tells you what a lender may be prepared to lend. Your own budget should also account for your ongoing expenses, other commitments, future plans and the financial buffer you want to keep.

What if my lender approves more than my budget?

Treat the lender's approval as information about your borrowing capacity, not as a recommendation about your spending. You can choose a lower purchase price if that leaves you more comfortable financially.

How much of your income should go towards a home?

There isn't one percentage of income that works for every household. Your comfortable housing cost depends on your income, other debts, dependants, living costs, savings goals and how much financial buffer you want to maintain. See the 30% rule explainer.

Is the 30% rule a good way to set a buying budget?

Not on its own. It is an old rule of thumb based on housing costs as a share of gross income. It can be a starting point for thinking about affordability, but it doesn't account for every household's income, debts, expenses, dependants or lifestyle.

How much should I leave as a buffer?

There isn't a universal buffer that suits every buyer. Consider what would happen if your income fell temporarily, interest rates increased, or you faced a large unexpected expense. The right buffer is one that leaves you able to handle those scenarios without immediately relying on additional debt.

How do I stress-test my mortgage repayments?

Model the repayments at several higher interest rates and see which ones you could still carry comfortably. The stress-test explainer walks through it.

What costs should I include?

Transfer duty where applicable, conveyancing, inspections, lender and registration fees, any loan costs that apply, moving costs and the ongoing costs of ownership. See budgeting for all the costs.

What should I do if I can't find a property within my budget?

Widen the search area, adjust the property type or timeframe, or improve your financial position, before simply raising the ceiling. See what to do if you can't find anything in budget.

How do I stick to my budget at auction?

Decide your ceiling in advance and write it down. See sticking to your budget at auction.