Objectives <p>This review aims to examine how gambling harms are measured by mapping existing self-report measures, analyzing methodologies for scoring gambling harms, and identifying key gaps to inform future research and practice.</p> Study design <p>Scoping review.</p> Methods <p>The scoping review coded data from 131 studies, analyzing harm measures, corresponding scoring methods, sample-related variables, and associated measures.</p> Results <p>(1) This review identified 41 distinct instruments used to measure gambling-related harm over the past two decades, encompassing gambling harm-specific surveys, problem gambling screening tools, custom questionnaires, and questionnaires on harm to affected others. (2) The current landscape reveals that most surveys capture only a subset of harm domains, with dichotomous scoring methods being widely used. (3) Additionally, harm measurement has been largely dominated by a few well-validated instruments, with criterion variables primarily focused on problem gambling severity, gambling engagement, and health-related constructs, and mainly delivered in the global north.</p> Conclusions <p>This review highlights discrepancies between conceptual frameworks and real-world practices in the measurement of gambling harm, exposing critical gaps in quantification that have implications for policy decisions, clinical assessments, and public health management. It also questions the generalizability of existing measures to non-WEIRD populations. Future research should prioritize rigorous domain selection, refinement of assessment items, and improvements in quantification methods to better serve the needs of policymakers, researchers, and clinicians. Additionally, establishing cross-cultural validity and utility of gambling harm measures outside of WEIRD contexts is also essential.</p>