Mobile platform providers have provided the ability to measure the time consumers spend on each app. This provides the opportunity to measure a consumer’s misestimation of their screen time which is a concept relevant to several mental health attributes such as depression, anxiety, and addiction. We provide additional evidence about the effect of objective screen time on mental health, but add a unique perspective on how screen time misestimation is determined by various mental health attributes. We collected data from a student sample (n=1005) who are from the demographic who most commonly use social media apps (18-29 yr olds). We measured our model across several of the most common platforms including Facebook, Instagram, Twitter, and YouTube to maximize the practical implications. The results indicate that mental health attributes can indeed be reflected by misestimations of screen time. However, this effect varies by social media platform.