Abstract: Capabilities are commonly used in planning and modelling of military power. In this work we introduce a method for modelling the impact of future technologies and new systems on capabilities. Based on probability theory, a mathematically tractable definition of capability is given. The model relates the capability of a system to the capability area (such as situational awareness, for example). We show how to “drill down” from high level capabilities into system capabilities. Relationships between different parts of the system of systems are defined in a quantified manner. The modelling method is demonstrated with data from a questionnaire where changes of capabilities were evaluated.