Understanding the true costs of digital financial services (DFS) is critical for policymakers, regulators, and researchers aiming to enhance financial inclusion and consumer protection. The Transaction Cost Index's Toolkit for Measuring the Real Costs of Digital Financial Services provides a practical framework for systematically measuring the financial and non-financial costs that consumers face when using DFS, including official fees, informal agent charges, and service quality factors. Drawing from a multi-country research initiative, this toolkit describes in detail four data collection options—tracking official prices, consumer interviews, and two mystery shopping approaches—allowing users to tailor their approach based on available resources and research objectives. Designed for adaptability, the toolkit equips users with the necessary guidance, tools, and best practices to conduct robust assessments and generate actionable insights for policy and market improvements.