Gemsmakers · Antique Dealer Tools
Antique Auction Maximum Bid Calculator for Target Profit
A profitable resale begins with a disciplined acquisition limit. Enter the likely resale proceeds and the costs that come before the item is ready to sell. The calculator solves for the maximum bid under two competing buyer-premium arrangements, making it easier to compare auction houses without letting a low-looking premium hide other costs.
Calculator
Enter your figures below. Results update from the assumptions you supply; check your agreement, fee schedule, and local requirements before making a decision.
How to use this tool
- Enter expected resale price and the percentage selling costs expected when you resell the item.
- Enter the target profit and non-auction costs such as restoration, transport, shipping, and fixed charges.
- Enter the estimated tax and payment-processing rates. Add the premium rate and fixed buyer fee for each auction option.
- Compare maximum bids and the total estimated acquisition cost at each limit. Treat negative or near-zero limits as a signal to avoid bidding for the target return.
Calculation method
Available budget for hammer and related percentage costs = expected resale × (1 − resale selling-fee rate) − restoration − shipping − other fixed costs − target profit. Maximum bid = (available budget − fixed buyer fee) ÷ [(1 + premium rate) × (1 + tax rate) × (1 + payment-fee rate)]. This uses a simplified compounded percentage-cost model.
Worked example
If resale proceeds after selling fees are 1,000 and restoration, shipping, other fixed costs, and target profit total 400, only 600 remains to cover acquisition. A premium, tax, and processing structure then lowers the maximum hammer bid below that 600 amount.
Important assumptions and limitations
- Tax and processing fees are modeled as compounded against the hammer plus premium. Replace this assumption with the auction house’s exact fee bases when available.
- Expected resale is uncertain. Use realistic completed-sale comparisons and discount for condition, restoration uncertainty, and selling time.
- A maximum bid is a ceiling, not a recommendation to bid up to that number.
Frequently asked questions
Why is maximum bid lower than resale price?
Resale proceeds must also cover selling fees, restoration, shipping, auction charges, taxes, and the profit target.
What if the result is negative?
Your target cannot be reached even with a zero hammer bid under the entered costs. Reassess the item or costs rather than treating zero as a viable bid.
How do the two premium options compare?
They apply each option’s premium rate and fixed buyer fee to the same resale and cost assumptions.
Why include target profit separately from target ROI?
Profit is an absolute amount. ROI measures profit relative to capital committed; this calculator targets profit directly, so use other investment tools if ROI is also a constraint.
Should I use asking prices as expected resale?
Completed sales are usually more informative. Asking prices may never convert into a sale and can overstate achievable proceeds.
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