The urgency of developing effective circularity assessment tools is reinforced at European and national levels, notably through initiatives like the EU Circular Economy Action Plan. However, existing metrics (e.g., MCI, BSI) and methodologies fall short of capturing the multifaceted nature of reuse scenarios. They struggle to address dynamic market conditions shaped by technological innovation and economic volatility, which are critical in determining the feasibility of reuse. Current reuse assessments rely heavily on resource-intensive audits conducted by specialised experts, limiting their scalability and accessibility. This paper presents the Reuse Viability Index (RVI), an innovative metric designed to evaluate and predict the sustainability of building component reuse. The RVI integrates all dimensions of sustainability-economic, environmental, social, and, uniquely, technical. The technical dimension is vital for construction reuse, encompassing parameters such as compliance with contemporary standards, deconstructability potential, and residual value. The primary objective of this research is to provide the genesis, development, and practical application of the RVI. The study seeks to answer a fundamental question: Can a single index be developed as a decision-making tool to measure and predict the reuse potential of building components in existing structures and at the project design stage for new constructions? The paper details the formulation of the RVI, explaining its conceptual basis and justification of the attributes critical for inclusion in such an index.