A growing body of evidence suggests that consumers are not fully informed about prices, contrary to a critical assumption of classical welfare analysis. We analyze a model in which consumers can vary in both their preferences and their information about prices. Given data on demand and the distribution of prices, we identify the set of possible values of the consumer surplus. Each surplus in this set can be rationalized with simple information structures and preferences. We extend the analysis to richer datasets and provide bounds on counterfactual demands.