ΞThe dynamic development of hydrogen-powered unmanned aerial vehicles (UAVs) has increased the need for consistent methods to assess their mass–energy characteristics, particularly in multirotor platforms, which are characterised by high and continuous power demand during hover-dominated operation. This study aims to identify mass–energy relationships in multirotor UAVs powered by proton exchange membrane fuel cells using an indicator-based comparative framework. The analysis was based on technical data obtained from manufacturer datasheets, technical reports, catalogues, and scientific publications, including maximum take-off weight, empty weight, payload, declared flight endurance, PEMFC rated power, hydrogen tank capacity, and storage pressure. A set of normalised indicators referenced to maximum take-off weight was used, including payload fraction, structural mass fraction, specific endurance, and PEMFC power-to-weight ratio. Pearson correlation analysis, simple linear regression, confidence intervals, and bootstrap resampling were applied to support the graphical interpretation of mass-dependent trends. The results show that most analysed platforms are characterised by structural mass fractions of 75–90% of MTOW, while payload fractions are typically within 10–25% of MTOW. Specific endurance generally falls within the range of 4–10 min/kg and shows a strong negative relationship with MTOW (r=−0.75, R^2=0.56), indicating that endurance efficiency per unit mass decreases as platform mass increases. In contrast, payload fraction and structural mass fraction showed weak or negligible linear dependence on MTOW, while the power-to-weight ratio exhibited greater dispersion, reflecting manufacturer-specific PEMFC sizing strategies. In addition, a power consistency ratio was introduced to compare estimated average power demand with PEMFC rated power and to assess the internal consistency of manufacturer-declared performance data. The proposed framework provides a first-order comparative tool for identifying mass–energy trade-offs, design constraints, and potential inconsistencies in commercial hydrogen-powered multirotor UAV platforms, rather than an experimentally validated predictive model.