In this article, a comparison focused on the power efficiency of analog, digital, and hybrid beamforming architectures is presented. A detailed equation-based model for the power consumption of the three architectures was developed for a receive phased array. The model clearly illustrates the contributions of various components to the total power consumption and how the power scales with various array parameters. A comparison of power consumption per beam-bandwidth product for the different array architectures shows the advantage of the hybrid approach for millimeter wave phased arrays with a large number of elements.