Abstract The devastating impacts of the 2004 Indian Ocean tsunami highlighted the need for an effective end-to-end tsunami early warning system in the region that connects the scientific components of warning with preparedness of institutions and communities to respond to an emergency. Essential to preparedness planning is knowledge of tsunami risks. In this study, development of an online tool named “INSPIRE” for tsunami inundation simulation and tsunami loss estimation is presented. The tool is designed to accommodate various accuracy levels of tsunami exposure data which will support the users to undertake preliminary tsunami risk assessment from the existing data with progressive improvement with the use of more detailed and accurate datasets. Sampling survey technique is introduced to improve the local vulnerability data with lower cost and manpower. The performance of the proposed methodology and the INSPIRE tool were tested against the dataset in Kamala and Patong municipalities, Phuket province, Thailand. The estimated building type ratios from the sampling survey show the satisfactory agreement with the actual building data at the test sites. Sub-area classification by land use can improve the accuracy of the building type ratio estimation. For the resulting loss estimation, the exposure data generated from detailed field survey can provide the agreeable results when comparing to the actual building damage recorded for the Indian Ocean tsunami event in 2004. However, lower accuracy exposure data derived from sampling survey and remote sensing can still provide a comparative overview of estimated loss.