How can sustainability in tourism be measured meaningful, and how can indicators support tangible change? Drawing on research experiences from Germany, the input explores three complementary approaches. First, it introduces a project coordinated by the German Tourism Association (DTV) to develop and test sustainability indicators for all tourism destinations, balancing scientific relevance with data availability and practical feasibility. Second, the specific case of greenhouse gas accounting in tourism is examined, highlighting how system boundaries, spatial scales and allocation principles influence assessments and their implications for (climate) action. Third, the input discusses a current global analysis of sustainability certifications and its role in assessing sustainability progress. Together, these examples invite reflection on the potential and limitations of measurement and its contribution to evidence-informed destination development.