In this study, powder flowability is assessed during granular compaction under free surface conditions by using Hausner ratio (HR) as flowability index. Different kinds of pharmaceutical and food powders were examined. The assessment of the flow properties of these powders according to HR is obtained using three compaction devices: DensiTap (R), GranuPack (R) and a homemade Vibratory device (particle dumper). The comparison of the HR values obtained with each compaction test provided a deeper understanding of HR. Here we show that HR is strongly dependent on the energy supplied to the system. This energy is the result of the vibration wave transmitted to the powder bed, and is strongly dependent on the vibration amplitude, i.e. on the device used. HR analysis as a function of the energy supplied to the powder bed allowed us to determine a maximal HR value, denoted ultimate HR (HRU), obtained when reaching a maximal compaction state. Thus, a new approach is proposed to determine flow behavior, through HR, as a function of the energy supplied to the powder bed. (C) 2019 Elsevier B.V. All rights reserved.