In this article, we estimate the total costs of the German participation in the Afghanistan war, both past and future. This is a hugely complex and uncertain calculation, which depends on several important assumptions. These assumptions pertain to the different cost channels and the shares of these channels that can be attributed to the German participation in the war. By calculating the costs of the German participation, we provide a framework for other researchers to do the same with respect to other countries. The article can function as a roadmap for researchers focusing on this topic. In the end we find that, in the most realistic of several possible scenarios regarding the duration and intensity of the German participation in the war in Afghanistan, the German share of the net present value of the total costs of the war ranges from 26 billion Euro to 47 billion Euro. These large ranges reflect the uncertainties with which the costs must be estimated. On an annual basis, we estimate that the German participation in the war costs between 2.5 and 3 billion Euro. This contrasts with the official war budget, which is little over 1 billion Euro for 2010, showing that governments may not adequately represent the costs of military action.