This paper examines the international scope and significance of John Calvin's correspondence within the broader framework of the ongoing project to produce a new critical edition of his letters. For the first time in the history of Calvin studies, this editorial initiative has generated a comprehensive digital database of all letters written by and addressed to Calvin. This systematically structured corpus provides a basis for quantitative and qualitative analysis of his epistolary network. Building on this newly available data, the present contribution investigates the geographical range, interlocutors, and thematic diversity of Calvin's correspondence, highlighting its fundamentally transnational character. The study first offers a synthetic overview of the database, mapping the principal regions, confessional communities, and social milieus represented in Calvin's letter exchanges. Particular attention is paid to patterns of communication that reveal the extent to which Geneva functioned as a nodal point in a wider Reformed and European intellectual network. In a second step, the paper turns to a close reading of selected letters that are especially illustrative of Calvin's international interests and engagement. These case studies demonstrate how his correspondence served not only theological and pastoral purposes but also diplomatic, political, and cultural functions. By combining large-scale data analysis with targeted textual interpretation, the article argues that Calvin's letter-writing was central to the formation of an early modern transconfessional and transregional Reformed world.