Auction Max Bid Calculator AU | Unpack Property

Work backwards from your available cash and loan pre-approval to estimate the maximum price you could bid at an Australian property auction, accounting for stamp duty at that price, any LMI if your deposit falls below 20%, and a safety buffer. Adjust inputs to see how changes to your deposit or buffer affect the ceiling bid.

Why is there no cooling-off at auction?
An auction contract is unconditional from the moment the hammer falls. Australian state laws exempt auctions from the cooling-off period that protects buyers in private treaty sales, because the public bidding process is meant to set a binding price.
What if the auctioneer keeps pushing past my max?
Stop bidding. The max bid this tool gives you is the absolute upper limit of what you can afford including stamp duty, fees and LMI. Going one bid above the max means borrowing more or eating into the buffer you set aside for surprises.
What is the buffer % for?
Auctions over-run their estimates regularly. The buffer protects you from hammer over-bids, post-auction inspection surprises, and rate-rise headroom. 3-5% is the safe planning anchor.
Why does stamp duty change at certain price points?
Australian stamp duty uses bracket tables - so paying $1 over a threshold can add thousands in duty. The tool flags when your max bid sits close to a bracket boundary so you don't accidentally cross it for a small headline jump.
Will I really need LMI if I'm a first home buyer?
LMI triggers when your loan exceeds 80% of the property price (LVR > 80%). FHB schemes like the federal Home Guarantee can waive it, but they have separate caps and aren't automatic. This tool shows the LMI cost so you can see whether bidding less to stay under 80% LVR pays off.
What happens if I'm short on the deposit on the day?
If you can't pay the 10% deposit (or whatever your contract specifies) on the day, the contract typically lapses and the property goes back on the market. Some states allow a deposit bond, but always confirm with your conveyancer before the auction.
Does this include pest + building inspection costs?
Those are usually paid before auction. Deduct them from the cash on hand input - what you bring to the auction should already exclude inspection costs you've spent.
Is this financial advice?
No. This is general information, not financial advice. See the disclaimer for the full statement.
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