Recognition of the health benefits of nature contact has increased. Simultaneously, growing numbers of people worldwide experience loneliness. There is a movement towards prescribing nature-based activities to improve/promote social connections, health, and quality of life. Yet, what constitutes a therapeutic nature dose is not well understood, due in part, to the lack of instruments that capture the characteristics of nature-based activities and measure ‘nature dose.’ We created a nature dose measurement tool to fill this gap by capturing various aspects of contact with nature and perceptions regarding park access, quality, naturalness, psychological distance to nature, and biodiversity. This tool will facilitate greater understanding of how natural areas, nature-based activities, and nature exposure reduce loneliness and promote health-related quality of life. Measuring nature dose with standardized tools and documenting benefits will generatethe evidence base needed to design, implement and evaluate nature-based social interventions for improving health and quality of life.•This tool captures the nature dose to reduce loneliness and promote quality of life.•Constructs range from park quality and access, to mood, to biodiversity perceptions.•The standardized nature dose tool will help design nature-based social interventions.