Injury Severity Score Calculator

About this calculator

The Injury Severity Score (ISS) is an anatomical scoring system used in trauma medicine to quantify the overall severity of a patient's injuries across multiple body regions. It's built from the Abbreviated Injury Scale (AIS), which rates injury severity in each of six body regions from 1 (minor) to 6 (unsurvivable). The ISS is calculated as the sum of the squares of the three highest AIS scores from three different body regions; if any single injury is rated AIS 6, the ISS is automatically set to the maximum of 75.

Developed in 1974 and still the most widely used anatomical injury severity measure, the ISS is used by trauma registries, emergency departments, and trauma surgeons to triage patients, predict mortality risk, and benchmark outcomes across hospitals and trauma systems. It's a research and epidemiological classification tool, not a diagnostic or treatment instrument — real-world scoring is always performed by trained clinicians reviewing actual injuries.