In many countries the calculation of habitable dwelling surface is characterised by a chaotic variety of calculation variants hardly comprehensible for the end user - sometimes not even reproducible for the expert. Therefore dossiers were analysed on the basis of a random choice in order to determine the method according to which the habitable dwelling surface was measured and to find out whether customers can scrutinize the calculations. The paper compares Sydney and Munich, where in both cases property prices are situated at the high end of the market.