# The hammer is the one number most auction houses do not print > Of 232 auction results in this archive, 53 carry no hammer price published by the house that sold the object. Here is how the missing number is recovered, and how it is checked. > The Study - 2026-09-27 > Canonical HTML: https://iconotheca.com/study/the-hammer-is-the-number-nobody-prints/ ## Key points - This archive holds 232 auction results. In 53 of them the house that sold the object never published a hammer price: 22 we recovered by arithmetic from the premium schedule, and 31 are still unresolved. - Christie's prints its buyer's premium schedule in full and then publishes only the premium-inclusive total, so the hammer has to be solved backwards out of the two numbers. - A recovered hammer is only worth carrying when it lands on a round bidding increment. That single check is the difference between arithmetic and a guess, and it is why every such figure here is labelled derived rather than confirmed. - Bonhams embeds the hammer in its own lot page data while showing the reader only the inclusive figure, so at least one house has the number and chooses not to display it. - Swann's own results post contradicts its own lot pages on two Migrant Mother prints, and the wrong figures travelled out of that post into a Wikimedia Commons file description and onward. ## The figure in the headline is not the figure anybody bid ## Christie's prints the schedule, then publishes only the total ## One print, two sales, and the arithmetic that recovers both hammers ## A recovered hammer has to land on a round bidding figure ## Bonhams has the hammer in the page and does not show it ## The house's own results post contradicted its own lot pages ## The estimate is not a forecast, and the house says so in writing ## A single lot result is not the whole transaction either ## What the missing number costs a reader ## Why this archive is free to read A price is evidence, and evidence has to say what it is. The number that circulates after a sale is an invoice total, set partly by a schedule the house wrote, and it is not the sentence the market spoke. The hammer is that sentence, and in about a quarter of the sales in this archive it has to be reconstructed from two documents to be read at all. We would rather print the reconstruction with its arithmetic shown and its label on it than pass off the easy figure as the real one. Where the schedule has gone offline and the sum cannot be closed, the record says unresolved, and it stays that way until somebody finds the document. ## Questions **What is the difference between the hammer price and the price realised?** The hammer price is the winning bid. The price realised is the hammer price plus the buyer's premium, a percentage the auction house charges the buyer on top of the bid. The price realised is the figure houses usually publish and the figure the press usually quotes. **Why do auction houses not publish the hammer price?** Most publish the premium-inclusive total because that is the amount the buyer pays, and their conditions of sale define sale totals on that basis. The premium schedule is published separately, so the hammer can usually be calculated from the two, but the house does not do the calculation for you. **How can a hammer price be calculated from the published total?** By applying the buyer's premium schedule printed in the conditions of sale for that sale in reverse. If a London total was GBP 1,225,800 under a schedule of 26 per cent to GBP 800,000 and 21 per cent above it, the first GBP 800,000 of hammer accounts for GBP 1,008,000 and the remaining GBP 217,800 divided by 1.21 gives GBP 180,000, so the hammer was GBP 980,000. **How do you know a calculated hammer price is right?** Because bidding moves in increments, a genuine hammer is a round figure. If the arithmetic returns a round number the schedule applied was almost certainly correct. If it returns a ragged one, the wrong schedule was used or the total includes charges the premium clause does not cover, and the hammer should be recorded as unknown. **Does an auction estimate predict the selling price?** No, and Christie's conditions of sale state plainly that no one may rely on an estimate as a prediction or guarantee of the actual selling price. Estimates are also quoted on a hammer basis and exclude the buyer's premium, so an estimate and a published result are not measured on the same basis. ## Sources - [1] Christie's, Conditions of Sale, London, August 2023, clause D1, The Buyer's Premium. Read in full as a PDF from the house's media library. - [2] Christie's, Conditions of Sale, New York, 19 October 2023, clause D1, The Buyer's Premium, and the estimates clause. Read in full as a PDF. - [3] Christie's, lot 19, Rembrandt, Christ crucified between the two Thieves (The Three Crosses), Old Masters Part I, London, 7 December 2023. - [4] Christie's, lot 20, Rembrandt, Christ crucified between the two Thieves (The Three Crosses), Exceptional Impressions: The Alan and Marianne Schwartz Collection, New York, 23 October 2024. - [5] Christie's, lot 17, Rembrandt, The Three Trees, Old Masters Part I, London, 7 December 2023, the lot whose inclusive result of GBP 869,400 had been misread onto the Three Crosses row. - [6] Swann Auction Galleries, lot 53, Dorothea Lange, Migrant Mother (horizontal variant), Fine Photographs, 11 March 2021. - [7] Swann Auction Galleries, lot 54, Dorothea Lange, Migrant Mother (vertical, the familiar frame), Fine Photographs, 11 March 2021. - [8] Swann Auction Galleries, results post for the sale of 11 March 2021, whose body text and caption disagree with each other and with the lot pages. - [9] Swann Auction Galleries, lot 114, Dorothea Lange, Migrant Mother, Fine Photographs, 20 October 2022, sold at USD 305,000 inclusive of premium. - [10] Christie's, via the Internet Archive, Conditions of Sale, New York, 2 September 2022, the schedule needed for the March 2023 Hokusai sale and since removed from the house's own site. - [11] Antiques and The Arts Weekly, 'Christie's Amends Buyer's Premium Thresholds', on the changes to the schedule that make the date of a sale decisive for this arithmetic.