In this paper, we explore how London residents understand, live, and experience their dwellings. Growing evidence shows that existing housing stock in the UK performs poorly in terms of functionality and flexibility. Policy and planning debates focus on the potential benefits of introducing standards for dwelling size while engaging less with broader questions of how to develop standards. Drawing on an online survey (n = 234) and in-depth interviews (n = 22) concerned with experiences of housing, we explore Londoners’ understandings of housing design sufficiency. Our findings show that experiences of dwellings, and understandings of those dwellings as sufficient for occupants’ needs, vary by household type and dwelling occupancy patterns. Moreover, social constructions of dwelling sufficiency are related not only to the size of dwellings, as often described and conceptualised by housing authorities in the UK, but also to the type, form, and layout of rooms. We further show that stay-at-home restrictions imposed in response to the Covid-19 pandemic challenged understandings of dwelling size and dwelling sufficiency. This prompts a discussion of the assumptions made in UK housing design regarding dwelling use, dwelling users, and future housing.