This article proposes to study the discreet ‘battles of numbers’ at workplace level, particularly exacerbated on pay equity, in relation to its potential additional costs for employers. Figures are at once a framework, an object and a resource for power struggles between social partners. This approach is inspired by ‘statactivism’, a research perspective that studies the ways and contexts in which statistics can become tools for social mobilization. In a European context where bargaining is increasingly decentralized to company level, we argue that researchers should pay attention to statistical resources and quantification skills of negotiators, both on the management and unions side. They should also include in their analytical framework the influence of experts and specialists who advise social partners on how to strategically produce and use gender‐sensitive statistics. In this article, two case studies allow us to open the ‘black box’ of equality bargaining, revealing challenges and controversies of gender pay reporting.