The initial steps in carrying out a feasibility analysis for a web project, based on information obtained interactively from a prospective client, are modelled as a rulebased expert system that draws on empirical formulas to provide a quantitative valuation of the clients replies. The model is centred in the pre-design phase, concerned in particular with ascertaining whether coherent aims, message, audience and services have been identified for the web project. The model is constructed empirically by means of a knowledge acquisitions process. The various data collected from the user are described, as well as the way in which these data are translated into quantitative values that subsequently play a role in the final diagnose for the web project. The system has been evaluated in two ways: system users were asked to provide feedback, and the experts who took part in the knowledge acquisition phase were asked to review system performance.