Externalities are changes in welfare caused by economic activities without these changes being reflected in market prices (Weinreich et al., 1998). In the field of transport these externalities arise when transport consumers/producers impose additional costs on society and its individuals without having to bear these costs themselves. External costs are externalities expressed in monetary terms and as such are being used in socio-economic evaluation to also take the sustainability aspects of measures into account. They express the costs society has to bear due to the transport activities. In literature a distinction is made between the external costs of transport (Schreyer et al., 2004): congestion, accidents, air pollution, noise, up- and downstream processes, land consumption, and climate change. By internalizing, these external effects become part of the decision making process of transport users, leading to a more efficient use of transport infrastructure. The European Commission has recommended this policy of internalization in several strategy papers such as the Green Paper on fair and efficient pricing (1995), the White Paper on the overall transport strategy (Time to decide, 2001), it's midterm review (Keep Europe moving, 2006), the Greening transport package (2008) and most recently in the new White Paper of 2011. The European Commission proposes a stepwise strategy for the internalization of external costs in all transport modes. A correct estimation of external costs is in this context essential knowledge to come to more sustainable transport and to be prepared when at the European level more stringent regulations will be implemented. The aim of this research is to develop a generic external cost calculator that can be used in projects in order to provide meaningful insights for both companies and governments on external costs related to transport activities.