Auction Math Toolkit
AuctionMath
Reference tools for checking buyer's premium math, all-in buyer costs, maximum bids, seller proceeds, quick calculator math, and historical currency conversions.
Check whether a reported auction price can already include buyer's premium based on the bid increment.
Auction Invoice Buyer Cost CalculatorEstimate all-in buyer cost from hammer price, buyer's premium, sales tax, shipping, handling, and additional fees.
Pre-Bid Planning Maximum Bid Ceiling CalculatorWork backward from a total budget and additional fees to find the highest hammer bid under auction terms.
Consignor Planning Seller Net Proceeds CalculatorEstimate seller proceeds after commission, insurance, photography, shipping, and additional fees.
Historical Rates Currency Exchange Rate CalculatorConvert historical currency amounts by selecting a date, amount, source currency, and target currency.
Historical Metal Prices Precious Metal Price CalculatorEstimate historical reference values for gold, silver, platinum, and palladium by weight and currency.
Quick Math Basic CalculatorUse a simple calculator with percent support, keyboard entry, clickable buttons, and editable history.
Auction calculators for bidding, invoices, and sale price research
AuctionMath provides practical, browser-based calculators for specific auction questions: whether a reported price could already include a buyer's premium, how auction fees affect an invoice, what bid stays within a budget, and how seller deductions change proceeds. Each tool page explains its inputs, calculation approach, an example, and important limitations so you can check whether its assumptions fit your situation. Historical currency and metal tools use identified third-party reference data and show the source date used.
Most auction calculations run in your browser. Basic calculator history and repeated historical lookups may be saved in browser storage; historical price and exchange-rate requests are sent to our API and data providers. See our Privacy Policy, Terms and Conditions, and About AuctionMath for more information. Results are estimates, not auction-house quotes, appraisal opinions, tax guidance, or professional advice.