Recommendation ITU-T Y.4903/L.1603 provides key performance indicators (KPIs) for smart sustainable cities (SSCs) and general principles for selecting KPIs to help cities achieve sustainable development goals (SDGs). This Recommendation provides a means to benchmarking and disseminating best practices in utilizing ICTs and other technologies to enhance cities’ sustainability and connect their smart strategies to the SDGs through an inclusive process. These KPIs are designed to evaluate the role and performance of Information Communication Technologies (ICTs) in the three dimensions of a city: Economics, Environment, and Society and Culture. The Indicators are uniquely coordinated to allow cities to measure their progress on reaching the ambitious targets set by the SDGs.