Vehicle safety systems may use occupant physiological information, e.g., occupant heights and weights to further enhance occupant safety. Determining occupant physiological information in a vehicle, however, is a challenging problem due to variations in pose, lighting conditions and background complexity. In this paper, we present two novel occupant height estimation approaches. In the first (2D) approach, by detecting the occupant’s eye level, the seating height of the occupant is first computed based on the distance from a conventional camera to the occupant’s head, which is then adjusted for the seat angles received from the seat angle sensors. In the second (3D) approach, we use additional depth information from a depth camera, e.g., Microsoft Kinect. In the 3D approach, we first detect human body and frontal face views (restricted by the Pitch and Roll values in the pose estimation) based on RGB and depth information. Next, the eye location (2D coordinates) is detected from frontal facial views by Haar-cascade detectors. The eye-location co-ordinates are then transferred into vehicle co-ordinates, and seated occupant eye height is estimated according to similar triangles and fields of view of Kinect. From the seated eye height, we estimate the occupant height on the basis of human ergonomics data.