A trace evidence comparison in which only class characteristics match generally is regarded as insufficient grounds for proving a connection between a defendant and a crime. However, it is interesting to consider mathematically the value of trace evidence in its combination with other evidence rather than in isolation. This type of analysis can be particularly important in the criminal justice process prior to a court appearance by helping an attorney support a hypothesis, version of events, or proposed crime scenario. The paper details a formula that permits numbers to be inserted and calculations made of the value that the evidence comparison will contribute to the case and an example of its application. Knowledge of the value of a trace evidence comparison prior to trial may implicate a defendant further or exonerate a suspect, indicate a stage in evidence testing when additional analyses produce diminishing rewards, or allow comparisons of the value of one species of trace evidence with another. Other researches have used Bayes' theorem to evaluate evidence of paternity and the likelihood of heart disease. Finally, forensic scientists can cite high evidence value of a trace evidence comparison in their testimony to augment other courtroom evidence. The appendix provides additional data on the mathematical analysis. Charts, graphs, and approximately 40 references are included.