Within a hedonic pricing model the preferences of Australian art purchasers are investigated. Emphasis is placed on the impact of an artwork's dimensions upon its auction price. A salient aspect of this is the first test of the 'golden ratio' hypothesis in a market situation. It is concluded that purchasers prefer paintings that deviate from the golden rule. The 'orientation' of works (portrait, landscape or square) as well as size also helps determine price. The impact of winning the Archibald portraiture prize (Australia's foremost art prize) is found to have significant and positive impacts on winning artists' prices. This suggests that purchasers are not fully informed. In addition a previously unsuspected relationship between artwork dimensions and Archibald prize winners was found. As well as purchasers' preferences, the artists' choices of the dimensions of their artworks are considered.