Too little is known about how much people share goods within a household, although this is an important determinant of the potential material comfort of individuals. We suggest a survey method that elicits people’s insights into how household sharing affects material comfort, equipped with a tool to test whether respondents understand the survey’s questions and communicate credible information. Using a sample of 2,042 German respondents, we find support for the survey’s effectiveness. We obtain estimates of household-size economies that indicate that richer households have an advantage in intra-household sharing, and we demonstrate how this affects the measurement of economic inequality and poverty.