An auction estimate is rarely a fixed price, but a price range within which the auction house expects a work of art to sell. Auction houses usually determine the auction estimate based on sales of similar objects of art in the past, combined with a careful analysis of the condition and collectible significance of the art. Although, particularly older pieces are being sold within some conservative market forces, even they are subject to ‘vogues’ or fashions in art buying, which in turn the auction houses also consider when establishing the price range.
Auction estimates are usually to find online or in printed auction catalogues before an art auction. If the price range is not listed, then it is the arithmetic mean or average of the highest and lowest number in the range.