Many design teams want to measure their impact yet struggle to move beyond dashboards, vanity metrics or isolated UX KPIs. In this session, two practitioners - a DesignOps leader and a senior freelance product designer - share the framework they built while collaborating at Doctolib to help designers understand, define and communicate design impact through data. We'll break down the foundations of data literacy for design: core metric types, the difference between leading and lagging indicators, and how interactions across a product create measurable outcomes. Through hands-on exercises in small groups, participants will reflect on signals in their own organizations, identify gaps in design measurement, and brainstorm a realistic, team-ready data strategy to shape both design quality and organisational decision making.