Crowding in public transport can be of major influence on passengers’ travel experience and therefore affect route and mode choice. Therefore, it is important to understand how crowding in urban public transport is perceived by passengers. The availability of individual smart card transactions allows us to gain insights in revealed trade-offs between travel time, transfers, waiting time and crowding in public transport route choice, instead of using stated preference experiments. Our study is the first in which crowding valuation for urban tram and bus travelling is determined fully based on revealed preference data. Based on the estimated discrete choice model, we conclude that crowding plays a significant role in passengers’ route choice in public transport. The crowding multiplier of in-vehicle time equals 1.16 when all seats are occupied. The crowding multiplier increases further from 1.16 to 1.40, in case of an average density of 4 standing passengers per 푚푚2. Besides, our estimation results confirm the existence of a tram bonus, in which in-vehicle time in a tram is perceived 0.6 times the in-vehicle time perceived in a bus. The insights gained from our study can support the decision-making process, by quantifying benefits of measures aiming to reduce crowding levels.@en