This Statistical Guideline aims to address the lack of a detailed, globally agreed statistical methodology for measuring plastic flows at the national, regional, and global levels. It provides guidance to practitioners on producing high-quality national-level statistics on plastics that are comparable across countries. With the continued increase in the production and consumption of plastics in recent decades, combined with a predominantly linear plastic economy and insufficient waste management, plastic pollution has become a global concern. Monitoring this issue is therefore essential. At the same time, producing statistics on plastics across the entire life cycle presents multiple challenges. Clear scoping and consistent definitions of plastics across society are necessary to support the development of robust statistics. Experts from the United Nations Environment Programme (UNEP) and the United Nations Institute for Training and Research (UNITAR), in collaboration and consultation with experts from other international organisations, national statistical offices, relevant ministries, academia, research institutes, and other entities of UN Member States, have developed the Statistical Guideline for Measuring Flows of Plastic throughout the Life Cycle. The Guideline proposes the boundaries of the plastic life cycle, defines key terms and concepts, and details the main elements for accounting for the production, trade, consumption, and waste of plastics. In developing the Statistical Guideline have been developed aligning to internationally agreed statistical standards, classifications, methodologies, and available data sources, with the aim of presenting a comprehensive picture of plastic flows throughout the life cycle. The Guideline is intended to provide substantial support to statistical offices and other relevant organisations responsible for producing statistics on plastics at the national, regional, and global levels. This Statistical Guideline represents a first step in addressing the absence of a detailed, globally agreed methodology for measuring plastic flows. Some aspects may require further discussion and refinement in future versions. Its application by statisticians and other relevant experts at the national level is expected to result in high-quality statistics on plastics that are comparable across national, regional, and global levels. These statistics will, in turn, support policymaking on strategically important issues, including, but not limited to, the 2030 Agenda for Sustainable Development, the circular economy, national source inventories on plastics, and plastic waste management.