This article describes the development of a model for academic libraries that is used to give detailed insight in the library's current financial structure and to quantify the impact of the transition to a digital environment. Moving forward, certain library services, activities and costs will decrease whereas others will increase. How will this affect the library budget? The project gave all participants detailed insight into library costs before and after such a transition, and showed that the added value of library services increases.The model is a co-operation of the libraries of the universities of Utrecht in the Netherlands, Lule in Sweden and Bremen in Germany. Elsevier commissioned this project; Atos KPMG Consulting delivered the methodology (Rapid Activity Based Costing) and financial expertise.