Purpose - The purpose of this research is to provide the scientific community with some quantitative data of relevance to the evaluation of two major citation databases. In addition, various aspects of the methodology of database coverage comparisons are discussed. Design/methodology/approach - Calculations of the overlaps between the journal lists of Web of Science and Scopus and some other major scientific databases are presented. Findings - The results provide some measures of the overall title coverage as well as the amount of unique material in the sources studied. Research limitations/implications - The journal title overlap calculations are based on journal lists provided by the database producers rather than searches in the databases themselves. Any inaccuracies in the lists may be reflected in the results. Also, the lists do not provide any information about the depth and consistency of the coverage. The nature of possible error sources is discussed. Originality/value - The methodology chosen allows comparatively quick comparisons between the contents of databases. This makes it suitable for analysis of trends in database coverage.