The human visual system produces the sensation of stereopsis with the help of depth cues. Disparity and blur (defocus) are widely accepted as the most important depth cues. The two cues are also known to have important effects on the visual discomfort caused by viewing stereoscopic content. However, the relationship between the combination of the two cues and visual comfort has rarely been investigated, especially when considering the effects of proximity cues, e.g., looming and motion parallax. In this study, various stereoscopic videos were compared with the planar videos corresponding to them. Each of the stereoscopic videos contained a set of depth cues, and the levels of the cues varied from video to video. The subjects were required to judge the relative visual comfort (RVC) for each pair, where RVC means the level of visual comfort of the first stimulus in the pair relative to the second one. The results showed that both disparity and blur have significant effects on RVC. The effects of disparity did not vary significantly with blur and proximity cues, and the effects of blur did not vary significantly with disparity and proximity cues. Based on these findings, the authors further built a regression model for the estimation of RVC from depth cues.