Self-efficacy, sense of belonging, and imposter phenomenon are all phenomena related to an individual’s perception of themselves and others. They are well-studied with mature, validated surveys, and they all have implications on personal performance, including in the CS education context. One question that none of the phenomena address, however, is how a student perceives their own performance relative to their peers. For example, none of these accepted measures considers a student who thinks that “everyone in this classroom is smarter than me.” In this paper, we propose a survey to measure a previously unexplored phenomenon experienced by computer science (CS) students. We call this phenomenon relative self-efficacy, and it measures how highly a student perceives their ability relative to their peers. No prior attempt has been made to measure how students rate themselves relative to others or to understand the causes and effects of these comparisons. We find that the underlying factors of our survey are distinct from those that measure sense of belonging. We also find that women are more likely to experience lower relative self-efficacy than men. Lastly, we find that GPA is weakly correlated with relative self-efficacy and suggest that there may be stronger, less obvious influences on relative self-efficacy.