In this paper, we devise a methodology that is able to objectively quantify the impact of tourism on the urban economy. This methodology takes various dimensions into account. First, to analyse the impact at sectoral level, it should bear in mind that tourism is a cross-sectional activity which affects many sectors, both directly and indirectly. Therefore, it is important to consider the impact of urban tourism on sectors traditionally defined as tourism-related, -that is, hotels, restaurants, shops, etc.- but also its impact on other sectors -for instance, textiles, food, construction, to name only a few- due to the intersectoral relationships that emerge. Second, we need to calculate the percentage of the turnover of each sector that is due to the tourism industry. Third, it is important to establish the geographic distribution of this impact: how is the effect shared between the city and its neighbouring areas QUESTION Finally, the effect of urban tourism should be quantified not only in terms of turnover, but also in terms of its contribution to GDP and employment.