The duration heuristic refers to the tendency to evaluate services based on their duration rather than on their content. We propose that consumers rely on the duration heuristic because it simplifies the evaluation process. In particular, the duration heuristic is most likely to be seen when the duration of the service experience is evaluable relative to other features and when duration is considered in relation to price. Across four experiments and a field study, we (a) provide demonstrations of the duration heuristic, (b) illustrate the biases that result as a consequence of its use, and (c) identify conditions under which consumers are more likely to use the heuristic.