Auction Max Bid Calculator
At an auction the hammer price is not what you pay: the buyer's premium, sales tax and shipping come on top. Enter what the item sells for, where you'll sell it and the profit you want — get the highest bid that still leaves it.
📸 At the stall? Skip the typing
Point your phone at the item: FlipTip identifies it, finds what it actually sold for, and shows this math — your profit after the fee of the marketplace you sell on, the most to pay and a clear buy or skip. 3 free scans a day, every paid plan free for 15 days.
Scan an item freeHow to work out your max bid
Start from the sold price
Use what it actually sold for recently — sold listings, not asking prices — and take off the fees and shipping of the marketplace you'll sell on, plus your profit or ROI.
Take off the auction's costs
Shipping or pickup from the auction comes off next. What is left is your all-in price: the bid plus the buyer's premium plus the sales tax.
Divide by the premium and tax
All-in price ÷ (1 + premium) ÷ (1 + tax) = your max bid. With a 15% premium and 7% tax, every $1 of bid costs you about $1.23.
Max bid on eBay flips — 15% buyer's premium, no tax, $15 auction shipping
| It sells for | For $20 profit | For 100% ROI |
|---|---|---|
| $60.00 | $2.99 | $3.67 |
| $100.00 | $33.04 | $18.70 |
| $150.00 | $70.61 | $37.48 |
| $200.00 | $108.17 | $56.26 |
| $300.00 | $183.30 | $93.83 |
| $500.00 | $333.57 | $168.96 |
Selling on eBay, most categories, free shipping with a $12 label and $1 of other costs per item. ROI is on everything you pay: bid, premium and auction shipping.
Fees used: eBay 13.6% of the total + $0.40 per order (most categories) · Mercari 10% · Poshmark 20%, $2.95 under $15 · Facebook Marketplace shipped 10%, min $0.80 · local cash sale free — checked October 2026. Details: eBay · Mercari · Poshmark · Facebook.
FAQ
How do I calculate a max bid with a buyer's premium?
Work out the most you can pay all-in (what it sells for, minus selling fees, shipping and your profit), take off the auction's shipping, then divide by 1 + the premium and 1 + the sales tax. Example: $100 all-in with a 15% premium and no tax → a max bid of $86.96.
What is a typical buyer's premium?
It varies by auction house and platform, often somewhere between 10% and 25% of the hammer price, sometimes with a separate online-bidding fee. It is always in the auction's terms — check it before you bid, it changes the max bid a lot.
Is sales tax charged on the buyer's premium?
Often yes: in many US states tax is charged on the hammer price plus the premium. This calculator assumes that; if your auction taxes only the hammer price, the real max bid is slightly higher.
Can FlipTip do this for a whole auction?
Yes — Sale X-Ray (Dealer plan, in every free trial) takes screenshots of the auction's photos, finds every lot worth money, prices the best ones from real sales and gives the max bid for each, after the premium, tax and shipping you enter.