Inertial sensors are included in most of the current smart devices and many researchers have identified their ability to be used for analyzing different parameters of human behavior. Among them, the pedestrian's step length provides very useful information for different applications, such as pedestrian dead reckoning positioning or gait analysis. During the last three decades, many step length estimation methods using inertial sensors have been proposed; however, there is no specific review work that reflects the current state of the art. In this paper, we will conduct a systematic and complete review that covers the whole workflow of tasks involved in the design, test, and evaluation of step length estimation methods based on inertial sensors. The main conclusion drawn from this review is that the lack of public data sets and standard methodologies to guide testing and evaluation makes it difficult to compare the different methods in a fair and robust way. Some reflections on how to move forward on this direction have been presented.