Two-dimensional approaches are widely used in the numerical thermal models of AlGaN/GaN high electron mobility transistors (HEMTs) to reduce the high computational cost of the three-dimensional approaches. The aforementioned simplified models predict inaccurate device temperatures with significant overestimation of the thermal resistance. In order to take advantage of the computational efficiency of the two-dimensional models, a correction procedure is necessary for the accurate representation of the actual device temperatures. In this paper, a novel correction method is introduced for this purpose. Correction technique presented in this study can be used to improve the accuracy of the multiscale numerical thermal device models. (C) 2017 Elsevier Ltd. All rights reserved.