Cognitions about one’s physical environment have a clear psychological impact on inhabitants. However, judgments of a setting’s spaciousness have been shown to be based not solely on the dimensions of the enclosure but also on a number of seemingly incidental environmental properties. Nevertheless, a theoretical integration and explanation of these various effects has been lacking. Across five experiments conducted in the laboratory and in virtual reality, we test an affordance-based account, which proposes that impressions of spaciousness are influenced by the wealth of behavioral opportunities offered by the environment. These experiments test how the functional arrangement of furniture (Experiments 1 and 2) and the priming of particular behaviors (Experiments 3a, 3b, and 3c) affect perceivers’ spatial impressions of the environment. These findings emphasize that cognitions about spaciousness are determined not by a passive calculation of area but are instead tied to its ability to facilitate physical activity.