The invention relates to a method (500) for ascertaining an installation angle (αInstall) between a roadway (170) on which a vehicle (100) travels and a detection direction (122) of a measurement or radar sensor (105). The method (500) has a step (510) of reading a plurality of reflection signals (125), each of which represents a measurement or radar beam (120) which has been emitted by a transmission unit (115) of the measurement or radar sensor (105) and each of which has been reflected on a different reflective section (130) of the vehicle (100). The reflection signals (125) have movement information on a movement direction of the vehicle (100) reflective section (130) on which the measurement or radar beam (120) has been reflected, and/or the reflection signals (125) have position information that represents the position (420) of the vehicle (100) reflective section (130) on which the measurement or radar beam (120) has been reflected. The method (500) additionally has a step (520) of detecting a movement direction component (v0) of the vehicle (100) reflective section (130) movement directions represented by the movement information from the plurality of reflection signals (125), wherein for said component all of the vehicle (100) reflective sections (130) are carrying out the same movement, and/or detecting a movement direction component (v0) for which the vehicle (100) reflective section (130) positions (420) represented by the position information are mapped at the same point in time while assuming the movement according to the movement direction component (v0) and form a shape at said point in time in a two-dimensional display, said shape having the greatest similarity to an L-shape (410). The method (500) lastly has a step (530) of determining the installation angle (αInstall) using the detected movement direction component (v0).