Towards Circular Economy Metrics: a Systematic Review

Abstract
The transition to a Circular Economy (CE) represents a critical rethinking of production and consumption systems, aiming to replace the prevailing linear model with regenerative cycles that prioritize resource efficiency, waste reduction, and environmental sustainability. However, existing performance indicators such as Gross Domestic Product (GDP) and conventional efficiency metrics are insufficient for capturing the complex interactions among resource flows, lifecycle impacts, and social equity core dimensions of circularity. This review examines the emergence and application of Circular Economy Metrics (CEMs) as tools for advancing measurement and strategic implementation across micro, meso, and macro levels. Through a systematic synthesis of the literature, the study evaluates key methodologies including Material Flow Analysis (MFA) and Life Cycle Analysis (LCA), alongside integrative frameworks such as the Circularity Index (CI) and the Circular-Based Quantity Assessment Tool (C.Q.A.T.). These tools are assessed for their effectiveness in operationalizing circularity, guiding sustainable business practices, and informing policy. Despite their promise, several barriers constrain the adoption of CEMs, including data limitations, technological challenges, lack of standardization, and fragmented regulatory environments. The review identifies best practices and highlights critical gaps, particularly regarding the integration of social and long-term economic dimensions. Through mapping current approaches and their limitations, this article contributes to the development of more holistic and actionable CE metrics. It offers a foundation for future research and policy innovation aimed at supporting systemic transitions to a robust and inclusive circular economy.