Start with sold revenue, not retail value
Retail value is usually the wrong anchor for auction inventory. A retailer’s list price does not tell you what an open-box, returned, incomplete, or locally sold item will produce. Use recent sold transactions from the marketplace where you realistically plan to sell. Asking prices only show what sellers hope to receive.
For a mixed lot, estimate the number of sellable units separately from the average sold price. If a lot contains 25 units and you expect only 80% to be complete and marketable, the revenue model should use 20 units—not 25.
Subtract the costs that happen after the auction
Gross sales are not cash profit. Marketplace fees, promoted listing fees, shipping paid by the seller, packing supplies, cleaning, testing, repairs, returns, disposal, and storage all reduce the money available for acquisition and profit.
If inventory is financed, include the cost of capital for the expected hold period. A credit card balance held for 90 days at a 24% annual percentage rate costs roughly 6% of the financed balance before compounding and card-specific details.
Convert the acquisition budget into a hammer bid
The auction’s buyer’s premium is added to the winning bid. A 15% premium turns a $1,000 hammer bid into $1,150 before tax, freight, or other charges. Fixed costs such as freight should be removed first; then divide the remaining budget by one plus the premium rate.
Sales tax can apply to the hammer price, premium, or both depending on the auction invoice and applicable exemption. Model the actual invoice treatment instead of assuming tax applies only to the bid. The Auction Profit & Max Bid Calculator handles premium, tax, freight, financing, and target profit together.
Worked maximum-bid example
Suppose a lot contains 25 units. You expect 80% to be sellable and the average sold price to be $45. Expected revenue is therefore 25 × 80% × $45, or $900.
- Expected revenue: $900
- Selling fees at 13%: $117
- Seller-paid shipping at $8 for 20 sellable units: $160
- Testing and supplies: $40
- Estimated financing cost: $20
- Required cash profit: $250
After those deductions, no more than $313 remains for the entire acquisition. If freight is $25 and the buyer’s premium is 15%, the maximum pre-tax hammer bid is approximately:
Rounding down to $250 creates an actual walk-away number. If bidding reaches $255, the deal has crossed the modeled limit even though the difference feels small in the moment.
Stress-test the two assumptions most likely to fail
Most auction misses come from overestimating sellable inventory or resale price. Run a downside case before bidding. Reduce the sellable rate, reduce average sold price, and lengthen the expected hold period. If a modest change eliminates the profit, the original bid has little margin for error.
For unmanifested pallets and storage units, require a larger return because condition and product mix are uncertain. For a clean, tested item with abundant sold data, a narrower uncertainty margin may be reasonable.
Five rules for setting a defensible bid
- Use completed sales from the channel you will actually use.
- Count damaged, incomplete, and slow-moving inventory in the sellable-rate assumption.
- Include the buyer’s premium, tax treatment, freight, labor, supplies, selling fees, returns, storage, and financing when material.
- Choose a cash-profit target before bidding begins.
- Write down the maximum hammer bid and stop when the auction crosses it.
Run the complete calculation
Use the free Auction Profit & Max Bid Calculator to calculate landed cost, expected profit, ROI, break-even sell-through, downside cases, financing cost, and the maximum hammer bid from your own assumptions.