An explosion in the production of cultural data reflects the increasing influence of calculative reason in the cultural sector, a situation criticised as the ‘instrumentalisation’ of culture. This article argues that this criticism concedes too much to the logics of calculation, and that power and political agency are being worked out in the sector in more complex ways in the wake of calculation than simply acquiescing to it. This is illustrated through an ethnographic account of the work of a new stratum of calculative cultural expertise that has emerged in the sector as calculation has become more important. These experts construct political agency through relational work that is concerned with both calculative and non-calculative matters, including the performance of objectivity, the mobilisation of various effects, and the construction of coalitions of actors.