In order to improve current rail timetabling processes, the suitability of train departure times for passengers should be included in timetable assessment. To achieve this, one possibility is to calculate the change in consumer and producer surplus (i.e., the economic welfare) resulting from departure time shifts in rail timetables. However, existing methods for this calculation are quite limited. To fill this gap, we propose a new method in the current paper. This method enables comparing most scenarios involved in interregional rail timetabling in terms of economic welfare. To this end, our method takes advantage of schedule-based models that allow assessing the impact of departure time shifts on the demand and valuation of each possible route using the timetable. As a proof of concept, we illustrate this method on a case study on the busiest Swedish interregional line. This case study shows the potential of the method to deliver detailed calculations with analysis of equity effects. To conclude, the method presented in this paper improves on the current literature, and it can be used to improve timetable optimisation algorithms or to better resolve conflicts between train path requests. © 2021 The Authors