Interconnect warming and temperature-gradient effect on chip performance and reliability are key topics of interest both for aluminium (Al) and copper (Cu) interconnects. For more demanding electromigration (EM) Idc specifications, it is essential to take the Joule-heating effect into account. In this paper, we present package-level Joule-heating characterisation results for Al-based interconnects. A comparison with Joule-heating measurements at wafer level is also presented. The root-mean-square (RMS) current-specification limits, Irms, obtained from wafer- and package-level measurements are compared with the values obtained from the pseudo-1D heat-dissipation equation. Different metal layers with various metal widths are studied. The results indicate that Joule heating at package level is higher compared to wafer level, which restricts the allowed Irms at package level. For wide lines in the lower metal layers, a deviation from the pseudo-1D model is observed in package-level measurements. While Irms limits are generally based on the pseudo-1D model, this study motivates further evaluation of interconnect reliability by determining realistic self-heating generated by package-level measurements.