In this methodological work, we introduce a new approach to evaluate the electric power consumption of a legged robot, by analyzing a single leg power consumption on a dedicated test bench, which doesn’t require any dynamic model of the robot and takes account of the non-linearities of the mechanism. The main idea is to split the measured data in two sets: energy consumption during the propulsion stroke (stance), and energy consumption during the leg return stroke (swing). This approach will be helpful to design and fabricate a low power consumption robotic leg and to evaluate the benefits with respect to a conventional leg design.