Indonesia, with the world’s third-longest coastline and over 17,000 islands, faces significant risks from multiple hazards, including sea-level rise, floods, drought, wildfires, storms, and land subsidence. Social vulnerability in coastal communities, influenced by socioeconomic factors such as age, wealth, health, gender, and ethnicity, is critical to understanding their capacity to manage and recover from these hazards. This research maps social vulnerability using demographic proxy-based assessment within a grid system, focusing on Bintan and the Seribu Islands as pilot sites. Utilising Principal Component Analysis (PCA), five key socioeconomic indicators, including population density, share of children, share of women, share of elderly and poverty rate, were identified to develop a Social Vulnerability Index (SoVI). The results indicate that the Seribu Islands are more socially vulnerable than Bintan, with significant differences in vulnerability patterns across urban and rural areas. Age and gender have a greater impact in urban areas of Bintan, whereas economic factors have a greater influence in rural areas. In the Seribu Islands, economic factors and high population density contribute significantly to vulnerability. This study highlights the importance of detailed spatial planning and targeted interventions to strengthen community resilience. The grid-based approach provides a more robust assessment, helping policymakers prioritise areas for disaster mitigation and support.