This paper presents results from research aimed at developing a real-time, ‘look ahead’ reliability measure of risk relative to tool wear or breakage. The objective is to present results of a successful research effort which has developed a real-time based conditional reliability (of individual tool survival) output from two inputs; (1) real-time thrust data from an individual tool, and (2) an expected thrust performance population model. The resulting conditional tool reliability measure developed is compatible with real-time tool management. It is used to estimate the conditional probability of toot survival in a drilling operation.