During the COVID-19 pandemic, the use of face masks by the public has helped to slow the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the community. Cloth masks have been recommended because of their effectiveness, availability, and reusability. Like other types of face masks, however, user discomfort while wearing cloth masks is thought to engender behaviors that limit the effectiveness of cloth masks as source control (e.g., adjusting or removing one's mask temporarily while in public). To design cloth masks that are more tolerable, a measurement instrument for assessing subjective user discomfort is needed. Across two studies, we identified and confirmed a two-dimensional factor structure underlying the discomfort of cloth masks - discomfort related to the breathability and discomfort related to the tightness of the mask against the face and head. Additionally, we provide replicable evidence that both factor-subscales predict the self-reported frequencies of problematic mask-wearing behaviors.