Recent findings suggest that it is harder to categorise the facial expressions of masked faces, than of unmasked faces. To date, studies of the effects of mask-wearing on emotion recognition have used categorisation paradigms: Authors have presented facial expression stimuli and examined participants’ ability to attach the correct label (e.g., happiness, disgust). While the ability to categorise particular expressions is important, this approach overlooks the fact that expression intensity is also informative during social interaction. Moreover, because categorisation paradigms force observers to pick a single label to describe their percept, any additional dimensionality within observers’ interpretation is lost. In the present study we adopted a complementary emotion-intensity rating paradigm to study the effects of mask-wearing on expression interpretation. We investigated how the presence of face masks affects the perceived emotional profile of prototypical expressions of happiness, sadness, anger, fear, disgust, and surprise. For each of these facial expressions, we measured the perceived intensity of all six emotions. We found that masks reduced the perceived intensity of intended emotions for all expressions except for anger. Additionally, masks increased the perceived intensity of non-intended emotions, for all expressions except surprise. These findings augment our understanding of how face-coverings impede non-verbal communication.