Organizers of major sports events regularly report impressive multibillion TV audiences to emphasize the success of their competitions, yet such claims are seldom substantiated with hard evidence, nor is it usually made clear what the numbers actually stand for. The aim of this paper is to provide a better insight into the ambiguity of reported audience sizes for sports events and to beg the question: What is the TV audience size for a live sports broadcast? By detailing seven pitfalls, we critically discuss the problems associated with a correct understanding of TV audiences for live sports broadcasts. We substantiate our findings with specific examples for various sports events. The paper demonstrates the relevance of a correct understanding of how TV audiences for sports broadcasts are determined and communicated, and the analysis of the pitfalls uncovers misunderstandings about reported TV audiences that have been largely ignored before. We also discuss the relevance of our insights for the growing body of academic literature in this field.