The Danish government has outlined a target of recycling 50% of total household waste by the year 2022 and transitioning to a circular economy in the future. Improving household waste sorting is an important consideration toward achieving this goal. This paper focuses on understanding existing waste sorting practices among Danish residents. We conducted a preliminary survey (N = 180) that assessed preference for sorting strategies and the types of waste sorted. Following this, a more detailed survey was conducted (N = 357) that assessed residents’ motivation to sort household waste, knowledge of local sorting requirements, information gaps that prevent effective sorting, and need for specific features in a mobile application. Results show that over one-third of respondents felt they needed additional waste sorting information. Respondents had fewer inaccuracies disposing items within a single waste stream (e.g., electronics waste) compared to items with mixed waste streams (e.g., milk carton with a plastic cap). Based on these findings, we propose the design of a mobile application that can potentially support household waste sorting in Denmark.