The phase trend in multi‐degree‐of‐freedom systems can be determined by an algorithm that tracks the relative signs of adjacent resonances in a modal expansion of transfer functions. This algorithm is expressed in analytical form for two‐dimensional systems. The analytical expression shows the transition from input function phase to the reverberant phase limit. The phase trend for two‐dimensional systems greatly exceeds that of the average response of such systems and the reason for this difference is analyzed.