This paper explores measurement of product performance with respect to circular economy principles. Potential indicators are assessed, with special attention given to questions such as: the variables that should be measured; how these variables should be assessed; and in which format they should be presented. The resulting considerations are used to develop a prototype whose design is informed through feedback from Circular Economy experts. The prototype uses a points-based questionnaire which converges into a simple final result with minimum and maximum limits. The selected approach is critically appraised, and its utility for decision-making discussed. The strengths include: ease of use; simplicity; speed; and an effective metaphor for the diffusion of circular economy principles. The limitations include: the opaque and potentially misleading nature of a single metric; superficial engagement with decision making; and the reliance on context specific assumptions. Future developments could include refining the approach to encourage deeper reflection, and generalization of the approach to different industry sectors or sustainability frameworks.