In this paper, we develop a framework for measuring the level of protection offered by relation hiding systems. The framework provides a uniform way to define a variety of privacy notions, including anonymity and unlinkability, by means of information-theoretic metrics. Moreover, based on the framework, a fairness metric for relation hiding systems is proposed. It is envisioned that, due to its generality, the framework will enable the analysis of privacy protecting systems in more detail, while the ability to measure a system's fairness circumvents in some cases the need to evaluate the privacy level that is provided to individual users, thereby reducing the number of times the metrics need to be evaluated by a potentially significant factor.