In this paper we propose a metric for finite processes in a probabilistic extension of CSP. The kernel of the metric cor- responds to trace equivalence and most of the operators in the process algebra is shown to satisfy non-expansiveness property with respect to this metric. We also provide an al- gorithm to calculate the distance between two processes to a prescribed discount factor in polynomial time. The al- gorithm has been implemented in a tool that helps us to measure processes automatically.