The Finance AlgorithmTFA

Auction Bidding Calculator

Calculator

Calculate your maximum auction bid including stamp duty, conveyancing, and inspection costs. Know your true budget before the hammer falls.

Free to useNo data storedAI insightsUpdated: February 2026

Auctions are high-pressure — the auctioneer is working against you, and it's easy to bid $20,000-$50,000 more than you can afford in the heat of the moment. The key to winning is knowing your absolute maximum bid BEFORE you arrive, accounting for stamp duty, conveyancing, inspections, and the deposit gap. This calculator works backwards from your budget to give you a precise maximum bid — so you can bid confidently without risking financial stress.

Enter Your Details

Enter Your Details

$

Your total available budget (deposit + borrowing capacity)

$

Cash you have available for deposit + costs

State determines stamp duty and legal costs

Affects stamp duty concessions and grant eligibility

$

Your maximum loan amount from your lender

Size of each bid you'd make at auction

Real-World Examples

First Home Buyer — Sydney

Budget: $900K. Deposit: $180K. Pre-approval: $720K. First home buyer in NSW.

Maximum bid: ~$842,000. Stamp duty: ~$33,340. Legal/inspection: ~$4,500. Deposit needed on the day (10%): ~$84,200. Remaining cash after deposit + costs: ~$58,000 (buffer). With FHB concession on homes under $800K, bid limit could rise to ~$860,000 if targeting sub-$800K range.

Frequently Asked Questions

Glossary

Reserve Price
The minimum price the vendor will accept. Not disclosed publicly. If bidding doesn't reach the reserve, the property is passed in.
Passed In
When bidding at auction doesn't reach the vendor's reserve price. The highest bidder gets first right to negotiate.
Vendor Bid
A bid made by the auctioneer on behalf of the seller to advance bidding. Must be declared and is only allowed before the reserve is met.

Disclaimer: This calculator provides estimates only and should not be relied upon for financial decisions. Interest rates, fees, and policies change frequently. Always verify information with lenders directly. This is general information, not personal financial advice. Consider seeking advice from a licensed mortgage broker or financial advisor.

Last updated: February 2026

How to Use
  1. Enter your total property budget (deposit + loan pre-approval).
  2. Add your available deposit cash.
  3. Select your state for stamp duty calculations.
  4. Choose your buyer type for applicable concessions.
  5. Enter your loan pre-approval amount.
  6. Get your maximum bid, required deposit, and a bid ladder showing increments.
Key Information
  • At auction you usually need a 10% deposit on the day (or 5% with negotiation).
  • Stamp duty, conveyancing ($1,500-$3,000), and inspections ($500-$1,500) must come from your cash — not the loan.
  • Your maximum bid = Total budget − stamp duty − legal costs − inspection costs.
  • If your maximum bid x 10% exceeds your cash deposit, your max bid is deposit-limited.
  • First home buyers may get stamp duty exemptions that raise their max bid.
Pro Tips
  • Write your maximum bid on your hand or a card — never go above it no matter what.
  • Budget for building & pest inspection ($500-$1,500) BEFORE the auction — once the hammer falls, there's no cooling-off period.
  • Ask the agent for a vendor statement/contract review by your solicitor before auction ($200-$500).
  • If your bid is $5K below someone else's, a strategic $1K increment can pressure them into stopping.
Avoid These Mistakes
  • Bidding your entire budget without allowing for stamp duty and legal costs — you'll be short $30,000+.
  • Not getting a building inspection before auction — no cooling-off period means you're stuck with defects.
  • Emotional overbidding — FOMO is the most expensive emotion in real estate.
  • Forgetting that the 10% deposit is due immediately — you need cleared funds on auction day.
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