Capacity of a link is a key metric for network design and management. Several tools for capacity measurement are present in the literature and they provide satisfying results when used over wired networks. Their performance over wireless links, however, is not as good, although the techniques they are based on should not suffer from changes at physical layer. This paper accounts for a performance assessment of four tools for capacity measurement, carried out over a wireless link located in a semi-anechoic chamber. The measurement station is designed to guarantee channel stationarity and interference-free measurement conditions, and the performance assessment takes advantage of a proper reference value for the measurand, which is obtained from physical layer measurements. The experimental analysis highlights that the performance of the tools is strongly dependent on the characteristics of the network interface cards that are used, whereas the reference value of capacity, measured at physical layer, does not actually change.