This study examines the performativity of using numbers in the context of human resource management (HRM). We use performativity as a theoretical lens to understand how such quantification affects individuals and work. We theorise three performative effects of quantification based on multiple case studies using internal documents and semi‐structured interviews. To do this we analysed six HRM quantification projects (including cases of algorithmic HRM) at a large French multinational corporation. Each use of quantification creates a specific form of performativity. Our work complements the sparse but growing literature on metrics, analytics and algorithms in Human Resources, focusing not on the kind of reality numbers represent but on how they impact different stakeholders.