Poster presentation at the 26th Soft Magnetic Materials Conference (SMM), to be held in Prague, Czech Republic, 4-7 September 2023. INRIM, Ampère Lab, and Politecnico di Torino (Polito) engaged in a comparison on the alternating and rotational magnetic loss measurements by means of laboratory-developed RSST systems. By this comparison, we could evaluate the progress made with respect to the previous exercise carried out in the ‘90s, which showed large lab-to-lab deviations of the measured rotational loss figures, running up to about 40 % [1]. The experiments were performed on 0.30 mm thick non-oriented Fe-(3.5 wt%)Si steel sheets from 5 Hz to 200 Hz and peak polarization values ranging between 1.0 T and 1.5 T. Alternating loss measurements, made by associating the Epstein test frame method with the H-coil method, permitted one to achieve a full sequence of reference values, by which the best values of the loss figures generated by the comparison and their deviations from the reference provide the participating laboratories with quantitative proof of the measuring capability achievable by use of their RSST setup. It is shown that deviations of the best RSST alternating loss values and the reference ones are contained in a band of ± 7 %. At the same time, it is obtained that the relative deviations of the rotational loss figures obtained in the different laboratories attain at most values around ± 5 %. [1] J. Sievert, H. Ahlers, M. Birkfeld, B. Cornut, F. Fiorillo, K.A. Hempel, T. Kochmann, A. Lebouc, T. Meydan, A. Moses, and A.M. Rietto, European intercomparison of measurements of rotational power loss in electrical sheet steel, J. Magn. Magn. Mater. 160 (1996), pp. 115 – 118.